U.S. patent number 8,053,040 [Application Number 12/529,841] was granted by the patent office on 2011-11-08 for liquid crystal composition, retardation plate, liquid crystal display device, and process for producing retardation plate.
This patent grant is currently assigned to FUJIFILM Corporation. Invention is credited to Takafumi Hosokawa, Yi Li, Hideyuki Nishikawa, Yuta Takahashi, Masataka Yoshizawa.
United States Patent |
8,053,040 |
Li , et al. |
November 8, 2011 |
Liquid crystal composition, retardation plate, liquid crystal
display device, and process for producing retardation plate
Abstract
A composition comprising at least one liquid crystal compound,
and at least one polymer is disclosed. The polymer comprises a
constitutional unit represented by a following formula (A) and a
constitutional unit derived from a monomer having a fluoroaliphatic
group(s): ##STR00001## wherein Mp represents a trivalent group
constituting fully or partially a polymer main chain; L represents
a single bond or a divalent linking group; and X represents a
substituted or non-substituted aromatic condensed ring group.
Inventors: |
Li; Yi (Minami-ashigara,
JP), Nishikawa; Hideyuki (Minami-ashigara,
JP), Takahashi; Yuta (Minami-ashigara, JP),
Yoshizawa; Masataka (Minami-ashigara, JP), Hosokawa;
Takafumi (Ashigarakami-gun, JP) |
Assignee: |
FUJIFILM Corporation
(Minato-Ku, Tokyo, JP)
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Family
ID: |
39980785 |
Appl.
No.: |
12/529,841 |
Filed: |
March 13, 2008 |
PCT
Filed: |
March 13, 2008 |
PCT No.: |
PCT/JP2008/055155 |
371(c)(1),(2),(4) Date: |
September 03, 2009 |
PCT
Pub. No.: |
WO2008/111685 |
PCT
Pub. Date: |
September 18, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20100078592 A1 |
Apr 1, 2010 |
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Foreign Application Priority Data
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Mar 14, 2007 [JP] |
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2007-064952 |
Feb 25, 2008 [JP] |
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2008-042759 |
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Current U.S.
Class: |
428/1.1;
252/299.4; 252/299.62; 428/1.2; 252/299.61 |
Current CPC
Class: |
C09K
19/348 (20130101); C09K 19/3497 (20130101); C09K
19/32 (20130101); C09K 19/3852 (20130101); G02F
1/133528 (20130101); G02B 5/3025 (20130101); C09K
2019/044 (20130101); C09K 2323/02 (20200801); C09K
2019/328 (20130101); Y10T 428/10 (20150115); Y10T
428/1005 (20150115); C09K 2323/00 (20200801); C09K
2019/0429 (20130101) |
Current International
Class: |
C09K
19/38 (20060101); C09K 19/32 (20060101); C09K
19/56 (20060101); C09K 19/34 (20060101) |
Field of
Search: |
;428/1.1,1.2
;252/299.01,299.5,299.62,299.4 ;349/117 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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63-205306 |
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Aug 1988 |
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JP |
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2-3407 |
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Jan 1990 |
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JP |
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2002-129162 |
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May 2002 |
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JP |
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2005-225990 |
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Aug 2005 |
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JP |
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2005-533902 |
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Nov 2005 |
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JP |
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2006-16599 |
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Jan 2006 |
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JP |
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2006-126768 |
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May 2006 |
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JP |
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2006-233191 |
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Sep 2006 |
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JP |
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2007-217656 |
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Aug 2007 |
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JP |
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2007-272185 |
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Oct 2007 |
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JP |
|
Other References
Notification Concerning Transmittal of International Preliminary
Report on Patentability (Form PCT/IB/326), International
Preliminary Report on Patentability (Form PCT/IB/373), Written
Opinion of the International Search Authority (Form PCT/ISA/237)
mailed in corresponding International Patent Application No.
PCT/JP2008/055155, Sep. 24, 2009, The International Bureau of WIPO,
Geneva, CH. cited by other .
International Search Report for PCT/JP2008/055155 completed May 14,
2008. cited by other .
Written Opinion for PCT/JP2008/055155 completed May 14, 2008. cited
by other.
|
Primary Examiner: Wu; Shean
Attorney, Agent or Firm: Buchanan Ingersoll & Rooney
PC
Claims
The invention claimed is:
1. A composition comprising: at least one liquid crystal compound,
and at least one polymer comprising a constitutional unit
represented by a following formula (A) and a constitutional unit
derived from a monomer having a fluoroaliphatic group(s):
##STR00071## wherein Mp represents a trivalent group constituting
fully or partially a polymer main chain; L represents a single bond
or a divalent linking group; and X represents a substituted or
non-substituted aromatic condensed ring group.
2. The composition of claim 1, wherein X in formula (A) represents
a substituted or non-substituted C.sub.5-30 aromatic condensed-ring
group.
3. The composition of claim 1, wherein X in formula (A) is a
substituted or non-substituted C.sub.10-20 naphthyl group.
4. The composition of claim 1, wherein Mp in formula (A) is a group
represented by formula Mp-1 or Mp-2; and L in formula (A)
represents a divalent linking group selected from the group
consisting of --O--, --NR.sup.a11-- (where R.sup.a11 is a hydrogen
atom or C.sub.1-10 aliphatic hydrocarbon group), --S--,
--C(.dbd.O)--, --S(.dbd.O).sub.2-- and a C.sub.1-20 substituted or
non-substituted alkylene group, or the group consisting of any
groups formed by linking at least two or more selected from the
former group with each other; ##STR00072## where "*" indicates the
position at which the group bonds to L in formula (A).
5. The composition of claim 1, wherein the unit derived from the
monomer having a fluoroaliphatic group(s) is a unit represented by
formula (B) shown below: ##STR00073## where Mp' represents a
trivalent group forming a main chain partially; L' represents a
single bond or a bivalent linking group; and Rf represents a
substituent having at least one fluorine atom therein.
6. The composition of claim 1, wherein the at least one liquid
crystal compound is a discotic liquid crystal compound.
7. The composition of claim 1, wherein the at least one liquid
crystal compound is a compound represented by formula (DI) shown
below: ##STR00074## where Y.sup.11, Y.sup.12 and Y.sup.13 each
independently represent a methine group or a nitrogen atom;
L.sup.1, L.sup.2 and L.sup.3 each independently represent a single
bond or a bivalent linking group; H.sup.1, H.sup.2 and H.sup.3 each
independently represent following formula (DI-A) or (DI-B); and
R.sup.1, R.sup.2 and R.sup.3 each independently represent following
formula (DI-R): ##STR00075## where, in formula (DI-A), YA.sup.1 and
YA.sup.2 each independently represent a methine group or a nitrogen
atom; XA represents an oxygen atom, a sulfur atom, a methylene
group or an imino group; * indicates the position at which the
formula bonds to any of L.sup.1 to L.sup.3; and ** indicates the
position at which the formula bonds to any of R.sup.1 to R.sup.3:
##STR00076## where, in formula (DI-B), YB.sup.1 and YB.sup.2 each
independently represent a methine group or a nitrogen atom; XB
represents an oxygen atom, a sulfur atom, a methylene group or an
imino group; * indicates the position at which the formula bonds to
any of L.sup.1 to L.sup.3; and ** indicates the position at which
the formula bonds to any of R.sup.1 to R.sup.3:
*-(-L.sup.21-F.sup.1).sub.n1-L.sup.22-L.sup.23-Q.sup.1 (DI-R))
where, in formula (DI-R), * indicates the position at which the
formula bonds to H.sup.1, H.sup.2 or H.sup.3 in formula (DI);
F.sup.1 represents a bivalent linking group having at least one
cyclic structure; L.sup.21 represents a single bond or a bivalent
linking group; n1 indicates an integer of from 0 to 4; L.sup.22
represents --O--, --O--CO--, --CO--O--, --O--CO--O--, --S--,
--NH--, --SO.sub.2--, --CH.sub.2--, --CH.dbd.CH-- or --C.ident.C--,
provided that, when the group has a hydrogen atom, the hydrogen
atom may be substituted with a substituent; L.sup.23 represents a
bivalent linking group selected from --O--, --S--, --C(.dbd.O)--,
--SO.sub.2--, --NH--, --CH.sub.2--, --CH.dbd.CH-- and
--C.ident.C--, and a group formed by linking two or more of these,
provided that, when the group has a hydrogen atom, the hydrogen
atom may be substituted with a substituent; and Q.sup.1 represents
a polymerizing group or a hydrogen atom.
8. The composition of claim 1, wherein the at least one liquid
crystal compound is a compound represented by formula (DII) or
(DIII) shown below: ##STR00077## where, in formula (DII), Y.sup.31,
Y.sup.32 and Y.sup.33 each independently represent a methine group
or a nitrogen atom; R.sup.31, R.sup.32 and R.sup.33 each
independently represent following formula (DII-R): ##STR00078##
where, in formula (DII-R), A.sup.31 and A.sup.32 each independently
represent a methine group or a nitrogen atom; X.sup.3 represents an
oxygen atom, a sulfur atom, a methylene group or an imino group;
F.sup.2 represents a bivalent cyclic linking group having a
6-membered cyclic structure; n3 indicates an integer of from 1 to
3; L.sup.31 represents --O--, --O--CO--, --O--CO--O--,
--O--CO--O--, --S--, --NH--, --SO.sub.2--, --CH.sub.2--,
--CH.dbd.CH-- or --C.ident.C--, provided that, when the group has a
hydrogen atom, the hydrogen atom may be substituted with a
substituent; L.sup.32 represents a bivalent linking group selected
from --O--, --S--, --C(.dbd.O)--, --SO.sub.2--, --NH--,
--CH.sub.2--, --CH.dbd.CH-- and --C.ident.C--, and a group formed
by linking two or more of these, provided that, when the group has
a hydrogen atom, the hydrogen atom may be substituted with a
substituent; and Q.sup.3 represents a polymerizing group or a
hydrogen atom; ##STR00079## where, in formula (DIII), Y.sup.41,
Y.sup.42 and Y.sup.43 where, in formula (DIII), each independently
represent a methine group or a nitrogen atom; R.sup.41, R.sup.42
and R.sup.43 each independently represent following formula
(DIII-A), (DIII-B) or (DIII-C): ##STR00080## where, in formula
(DIII-A), A.sup.41, A.sup.42, A.sup.43, A.sup.44, A.sup.45 and
A.sup.46 each independently represent a methine group or a nitrogen
atom; X.sup.41 represents an oxygen atom, a sulfur atom, a
methylene group or an imino group; L.sup.41 represents --O--,
--O--CO--, --CO--O--, --O--CO--O--, --S--, --NH--, --SO.sub.2--,
--CH.sub.2--, --CH.dbd.CH-- or --C.ident.C--, provided that, when
the group has a hydrogen atom, then the hydrogen atom may be
substituted with a substituent; L.sup.42 represents a bivalent
linking group selected from --O--, --S--, --C(.dbd.O)--,
--SO.sub.2--, --NH--, --CH.sub.2--, --CH.ident.CH-- and a group
formed by linking two or more of these, provided that, when the
group has a hydrogen atom, then the hydrogen atom may be
substituted with a substituent; and Q.sup.4 represents a
polymerizing group or a hydrogen atom: ##STR00081## where, in
formula (DIII-B), A.sup.51, A.sup.52, A.sup.53, A.sup.54, A.sup.55
and A.sup.56 each independently represent a methine group or a
nitrogen atom; X.sup.52 represents an oxygen atom, a sulfur atom, a
methylene group or an imino group; L.sup.51 represents --O--,
--O--CO--, --CO--O--, --O--CO--O--, --S--, --NH--, --SO.sub.2--,
--CH.sub.2--, --CH.dbd.CH-- or provided that, when the group has a
hydrogen atom, then the hydrogen atom may be substituted with a
substituent; L.sup.52 represents a bivalent linking group selected
from --O--, --S--, --C(.dbd.O)--, --SO.sub.2--, --NH--,
--CH.sub.2--, --CH.dbd.CH-- and --C.ident.C--, and a group formed
by linking two or more of these, provided that, when the group has
a hydrogen atom, then the hydrogen atom may be substituted with a
substituent; and Q.sup.5 represents a polymerizing group or a
hydrogen atom: ##STR00082## where, in formula (DIII-C), A.sup.61,
A.sup.62, A.sup.63, A.sup.64, A.sup.65 and A.sup.66 each
independently represent a methine group or a nitrogen atom;
X.sup.63 represents an oxygen atom, a sulfur atom, a methylene
group or an imino group; L.sup.61 represents --O--, --O--CO--O--,
--CO--O--, --O--CO--O--, --S--, --NH--, --SO.sub.2--, --CH.sub.2--,
--CH.dbd.CH-- or --C.ident.C--, provided that, when the group has a
hydrogen atom, then the hydrogen atom may be substituted with a
substituent; L.sup.62 represents a bivalent linking group selected
from --O--, --S--, --C(.dbd.O)--, --SO.sub.2--, --NH--,
--CH.sub.2--, --CH.dbd.CH-- and --C.ident.C--, and a group formed
by linking two or more of these, provided that, when the group has
a hydrogen atom, then the hydrogen atom may be substituted with a
substituent; and Q.sup.6 represents a polymerizing group or a
hydrogen atom.
9. The composition of claim 7, comprising a first liquid crystal
compound represented by formula (DI) and a second liquid crystal
compound other than that represented by formulae (DI).
10. The composition of claim 9, wherein the second compound is a
compound represented by formula (T) shown below: ##STR00083## where
M represents a bivalent linking group, which may be the same or
different; and Q.sup.7 represents a polymerizable group or a
hydrogen atom, which may be the same or different.
11. A retardation plate comprising an optically anisotropic layer
formed of a composition of claim 1.
12. A liquid crystal display device comprising a retardation plate
as set forth in claim 11.
13. A method of producing a retardation plate comprising forming an
optically anisotropic layer by using a composition of claim 1.
14. An agent for controlling tilt angles, which is a polymer
comprising a constitutional unit represented by formula (A) and a
constitutional unit derived from a monomer having a fluoroaliphatic
group(s): ##STR00084## where Mp represents a trivalent group
forming a main chain fully or partially; L represents a single bond
or a bivalent linking group; and X represents a substituted or
non-substituted aromatic condensed-ring group.
15. The composition of claim 8, comprising a first liquid crystal
compound represented by formula (DII) or (DIII) and a second liquid
crystal compound other than that represented by formulae (DII) and
(DIII).
16. The composition of claim 15, wherein the second compound is a
compound represented by formula (T) shown below: ##STR00085## where
M represents a bivalent linking group, which may be the same or
different; and Q.sup.7 represents a polymerizable group or a
hydrogen atom, which may be the same or different.
Description
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a composition, a polymer and a
tilt angle controlling agent that are useful for producing an
optically anisotropic layer, a retardation plate produced by using
the same, and a process for producing the retardation plate. The
invention also relates to a liquid crystal display device having
the retardation plate.
2. Related Art
A liquid crystal display device generally comprises a first
polarizing plate and a second polarizing plate provided with a
liquid crystal cell intervening therebetween, and the liquid
crystal cell has a pair of substrates and a liquid crystal layer
containing a rod-like liquid crystal compound intervening
therebetween. It has been known in the art that birefringence
occurring in the liquid crystal cell employing a rod-like liquid
crystal compound is compensated with an optical compensation sheet
having an optically anisotropic layer formed with a discotic liquid
crystal compound (such as
2,3,6,7,10,11-hexa(4-(4-acryloyloxyhexyloxy)benzoyloxy)-triphenylene).
In this case, there are some cases where the phase difference
cannot be compensated over the entire wavelength range of light due
to difference in wavelength dispersibility between the rod-like
liquid crystal compound and the discotic liquid crystal compound to
cause discoloration (such as failure in black color).
A trisubstituted benzene compound substituted with a heterocyclic
group has also been reported as the discotic liquid crystal
compound (in Macromolecular Crystals and Liquid Crystals, vol. 370,
p. 391 (2001). However, it is difficult to attain low wavelength
dispersibility, i.e., making the wavelength dispersion close to
constant, by using the compound, and such a compound is demanded
that has smaller wavelength dispersibility (i.e., a small value of
(Re of short wavelength (e.g., 450 nm))/(Re of long wavelength
(e.g., 650 nm))).
While the difference in wavelength dispersibility has been mainly
discussed herein, the retardation value Re(.lamda.) of the
retardation plate is also important. It is necessary to determine
the retardation Re(.lamda.) of the retardation plate corresponding
to the optical property of the liquid crystal cell to be
compensated. The retardation (.DELTA.nd) is the product of the
refractive index anisotropy (.DELTA.n) of the optically anisotropic
layer and the thickness (d) of the optically anisotropic layer. In
the case where the optically anisotropic layer has a larger
refractive index anisotropy (.DELTA.n), the liquid crystal cell can
be compensated even with the layer having a smaller thickness (d).
In a retardation plate produced by fixing the orientation of liquid
crystals, the retardation (Re) varies depending on the orientation
angle (i.e., the tilt angle and the mean tilt angle) of the
oriented liquid crystal, and it is therefore necessary to control
the orientation angle.
JPA No. 2002-129162 proposes a compound having a ring structure
represented by the specific formula as a liquid crystal orientation
accelerator. JPA No. 2006-16599 proposes a polymerizable liquid
crystal composition containing a (meth)acrylate copolymer (H)
having a side chain containing a fluorine group and a side chain
having a group containing a ring structure represented by the
specific formula.
However, these conventional orientation controlling agents do not
exhibit orientation controlling capability to any liquid crystal
compound, and are insufficient as an orientation controlling agent,
for example, for the aforementioned tri-substituted benzene type
discotic liquid crystal compound substituted with a heterocyclic
group. In particular, it is difficult to subject the
tri-substituted benzene type discotic liquid crystal compound
substituted with a heterocyclic group to hybrid orientation with a
low mean tilt angle (for example, 40.degree. or less), and an
orientation controlling agent capable of controlling such an
orientation state is demanded.
In the case where an optically anisotropic film or the like is
produced by curing a liquid crystal molecule through polymerization
or the like, it is demanded that the tilt angle is not changed upon
fluctuation in temperature on curing, from the standpoint of
production stability of the optically anisotropic film or the like.
However, although the tilt angle of the liquid crystal molecule can
be controlled with the conventional orientation controlling agent,
the temperature dependency of the tilt angle thereof is large to
deteriorate the production stability, and improvement thereof is
demanded.
SUMMARY OF THE INVENTION
One object of the invention is to provide a composition, a polymer
and a tilt angle controlling agent that are useful for producing
stably an optically anisotropic layer contributing to optical
compensation of a liquid crystal display device. More specifically,
an object of the invention is to provide a composition, a polymer
and a tilt angle controlling agent that are useful for producing an
optically anisotropic layer exhibiting optical anisotropy owing to
hybrid orientation of a liquid crystal compound, in a stable manner
with no defect (or reduced defects) caused by orientation failure
and the like of the optical characteristic values.
The invention is also to provide a retardation plate that is useful
for optical compensation of a liquid crystal display device, and a
process for producing the retardation plate.
The invention is further to provide a liquid crystal display device
that contains the retardation plate and exhibits favorable display
characteristics.
In one aspect, the invention provides a composition comprising:
at least one liquid crystal compound, and
at least one polymer comprising a constitutional unit represented
by a following formula (A) and a constitutional unit derived from a
monomer having a fluoroaliphatic group(s):
##STR00002##
wherein Mp represents a trivalent group constituting fully or
partially a polymer main chain; L represents a single bond or a
divalent linking group; and X represents a substituted or
non-substituted aromatic condensed ring group.
In the formula, X may represent a substituted or non substituted
C.sub.5-30 aromatic condensed-ring group, or may be a substituted
or non-substituted C.sub.10-20 naphthyl group.
In the formula, Mp may be a group represented by formula Mp-1 or
Mp-2; and L may represent a divalent linking group selected from
the group consisting of --O--, (where R.sup.a11 is a hydrogen atom
or C.sub.1-10 aliphatic hydrocarbon group), --S--, --C(.dbd.O)--,
--S(.dbd.O).sub.2-- and a C.sub.1-20 substituted or non-substituted
alkylene group, or the group consisting of any groups formed by
linking at least two or more selected from the former group with
each other;
##STR00003##
where "*" indicates the position at which the group bonds to L in
formula (A).
The unit derived from the monomer having a fluoroaliphatic group(s)
may be a unit represented by formula (B) shown below:
##STR00004##
where Mp' represents a trivalent group forming a main chain
partially; L' represents a single bond or a bivalent linking group;
and Rf represents a substituent having at least one fluorine atom
therein.
The at least one liquid crystal compound may be a discotic liquid
crystal compound; and may be a compound represented by formula (DI)
shown below:
##STR00005##
where Y.sup.11, Y.sup.12 and Y.sup.13 each independently represent
a methine group or a nitrogen atom; L.sup.1, L.sup.2 and L.sup.3
each independently represent a single bond or a bivalent linking
group; H.sup.1, H.sup.2 and H.sup.3 each independently represent
following formula (DI-A) or (DI-B); and R.sup.1, R.sup.2 and
R.sup.3 each independently represent following formula (DI-R):
##STR00006##
where, in formula (DI-A), YA.sup.1 and YA.sup.2 each independently
represent a methine group or a nitrogen atom; XA represents an
oxygen atom, a sulfur atom, a methylene group or an imino group; *
indicates the position at which the formula bonds to any of L.sup.1
to L.sup.3; and ** indicates the position at which the formula
bonds to any of R.sup.1 to R.sup.3:
##STR00007##
where, in formula (DI-B), YB.sup.1 and YB.sup.2 each independently
represent a methine group or a nitrogen atom; XB represents an
oxygen atom, a sulfur atom, a methylene group or an imino group; *
indicates the position at which the formula bonds to any of L.sup.1
to L.sup.3; and ** indicates the position at which the formula
bonds to any of R.sup.1 to R.sup.3:
*-(-L.sup.21-F.sup.1).sub.n1-L.sup.22-L.sup.23-Q.sup.1 (DI-R))
where, in formula (DI-R), * indicates the position at which the
formula bonds to H.sup.1, H.sup.2 or H.sup.3 in formula (DI);
F.sup.1 represents a bivalent linking group having at least one
cyclic structure; L.sup.21 represents a single bond or a bivalent
linking group; n1 indicates an integer of from 0 to 4; L.sup.22
represents --O--, --O--CO--, --CO--O--, --O--CO--O--, --S--,
--NH--, --SO.sub.2--, --CH.sub.2--, --CH.ident.CH-- or provided
that, when the group has a hydrogen atom, the hydrogen atom may be
substituted with a substituent; L.sup.23 represents a bivalent
linking group selected from --O--, --S--, --C(.dbd.O)--,
--SO.sub.2--, --NH--, --CH.sub.2--, --CH.dbd.CH-- and
--C.ident.C--, a group formed by linking two or more of these,
provided that, when the group has a hydrogen atom, the hydrogen
atom may be substituted with a substituent; and Q.sup.1 represents
a polymerizing group or a hydrogen atom.
The at least one liquid crystal compound may be a compound
represented by formula (DII) or (DIII) shown below:
##STR00008##
where, in formula (DII), Y.sup.31, Y.sup.32 and Y.sup.33 each
independently represent a methine group or a nitrogen atom;
R.sup.31, R.sup.32 and R.sup.33 each independently represent
following formula (DII-R):
##STR00009##
where, in formula (DII-R), A.sup.31 and A.sup.32 each independently
represent a methine group or a nitrogen atom; X.sup.3 represents an
oxygen atom, a sulfur atom, a methylene group or an imino group;
F.sup.2 represents a bivalent cyclic linking group having a
6-membered cyclic structure; n3 indicates an integer of from 1 to
3; L.sup.31 represents --O--, --O--CO--, --CO--O--, --O--CO--O--,
--S--, --NH--, --SO.sub.2--, --CH.sub.2--, --CH.dbd.CH-- or
--C.ident.C--, provided that, when the group has a hydrogen atom,
the hydrogen atom may be substituted with a substituent; L.sup.32
represents a bivalent linking group selected from --O--, --S--,
--C(.dbd.O)--, --SO.sub.2--, --NH--, --CH.sub.2--, --CH.dbd.CH--
and --C.ident.C--, a group formed by linking two or more of these,
provided that, when the group has a hydrogen atom, the hydrogen
atom may be substituted with a substituent; and Q.sup.3 represents
a polymerizing group or a hydrogen atom;
##STR00010##
where, in formula (DIII), Y.sup.41, Y.sup.42 and Y.sup.43 each
independently represent a methine group or a nitrogen atom;
R.sup.41, R.sup.42 and R.sup.43 each independently represent
following formula (DIII-A), (DIII-B) or (DIII-C):
##STR00011##
where, in formula (DIII-A), A.sup.41, A.sup.42, A.sup.43, A.sup.44,
A.sup.45 and A.sup.46 each independently represent a methine group
or a nitrogen atom; X.sup.41 represents an oxygen atom, a sulfur
atom, a methylene group or an imino group; L.sup.41 represents
--O--, --O--CO--, --CO--O--, --O--CO--O--, --S--, --NH--,
--SO.sub.2--, --CH.sub.2--, --CH.dbd.CH-- or --C.ident.C--,
provided that, when the group has a hydrogen atom, then the
hydrogen atom may be substituted with a substituent; L.sup.42
represents a bivalent linking group selected from --O--, --S--,
--C(.dbd.O)--, --SO.sub.2--, --NH--, --CH.sub.2--, --CH.dbd.CH--
and --C.ident.C--, and a group formed by linking two or more of
these, provided that, when the group has a hydrogen atom, then the
hydrogen atom may be substituted with a substituent; and Q.sup.4
represents polymerizing group or a hydrogen atom:
##STR00012##
where, in formula (DIII-B), A.sup.51, A.sup.52, A.sup.53, A.sup.54,
A.sup.55 and A.sup.56 each independently represent a methine group
or a nitrogen atom; X.sup.52 represents an oxygen atom, a sulfur
atom, a methylene group or an imino group; L.sup.51 represents
--O--, --O--CO--, --CO--O--, --O--CO--O--, --S--, --NH--,
--SO.sub.2--, --CH.sub.2--, --CH.dbd.CH-- or --C.ident.C--,
provided that, when the group has a hydrogen atom, then the
hydrogen atom may be substituted with a substituent; L.sup.52
represents a bivalent linking group selected from --O--, --S--,
--C(.dbd.O)--, --SO.sub.2--, --NH--, --CH.sub.2--, --CH.dbd.CH--
and --C.ident.C--, and a group formed by linking two or more of
these, provided that, when the group has a hydrogen atom, then the
hydrogen atom may be substituted with a substituent; and Q.sup.5
represents a polymerizing group or a hydrogen atom:
##STR00013##
where, in formula (DIII-C), A.sup.61, A.sup.62, A.sup.63, A.sup.64,
A.sup.65 and A.sup.66 each independently represent a methine group
or a nitrogen atom; X.sup.63 represents an oxygen atom, a sulfur
atom, a methylene group or an imino group; L.sup.61 represents
--O--, --O--CO--, --CO--O--, --O--CO--O--, --S--, --NH--,
--SO.sub.2--, --CH.sub.2--, --CH.dbd.CH-- or --C.ident.C--,
provided that, when the group has a hydrogen atom, then the
hydrogen atom may be substituted with a substituent; L.sup.62
represents a bivalent linking group selected from --O--, --S--,
--C(.dbd.O)--, --SO.sub.2--, --NH--, --CH.sub.2--, --CH.dbd.CH--
and --C.ident.C--, a group formed by linking two or more of these,
provided that, when the group has a hydrogen atom, then the
hydrogen atom may be substituted with a substituent; and Q.sup.6
represents a polymerizing group or a hydrogen atom.
As one embodiment, there is provided the composition comprising a
first liquid crystal compound represented by formula (DI), (DII) or
(DIII) and a second liquid crystal compound other than that
represented by formulae (DI), (DII) and (DIII). According this
embodiment, the second compound may be selected form formula (T)
shown below:
##STR00014##
where M represents a bivalent linking group, which may be the same
or different; and Q.sup.7 represents a polymerizable group or a
hydrogen atom, which may be the same or different.
In another aspect, the invention provides a retardation plate
comprising an optically anisotropic layer formed of the
composition; a liquid crystal display device comprising the
retardation plate; a method of producing a retardation plate
comprising forming an optically anisotropic layer by using the
composition; a polymer comprising a unit represented by formula (A)
and a unit represented by formula (B):
##STR00015##
where Mp represents a trivalent group forming a main chain
partially; L represents a single bond or a bivalent linking group;
and X represents a substituted or non-substituted aromatic
condensed-ring group;
##STR00016##
where Mp' represents a trivalent group forming a main chain
partially; L' represents a single bond or a bivalent linking group;
and Rf represents a substituent having at least one fluorine atom
therein; and
an agent for controlling tilt angles, which is a polymer comprising
a unit represented by formula (A) and a unit derived from a monomer
having a fluoroaliphatic group(s):
##STR00017##
where Mp represents a trivalent group forming a main chain fully or
partially; L represents a single bond or a bivalent linking group;
and X represents a substituted or non-substituted aromatic
condensed-ring group.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross sectional view showing a representative
embodiment of a light diffusion film.
In the drawing, reference numerals mean as follows:
TABLE-US-00001 101 light diffusion film 102 transparent base film
103 light diffusion layer 104 translucent resin 140 translucent
resin 141 first translucent fine particle 142 second translucent
fine particle
PREFERRED EMBODIMENT OF THE INVENTION
The invention will be described in detail below. The expression
"from a lower value to an upper value" referred herein means that
the range intended by the expression includes both the lower value
and the upper value.
At first, the definitions of "Re(.lamda.)", "Rth(.lamda.)" and
"tilt angle" are explained.
(Measure of Re(.lamda.) and Rth(.lamda.))
In the description, Re(.lamda.) and Rth(.lamda.) each indicate the
in-plane retardation and the thickness direction retardation of the
film at a wavelength .lamda.. Re(.lamda.) is measured by applying a
light having a wavelength of .lamda. nm in the normal direction of
the film, using KOBRA-21ADH or WR (by Oji Scientific Instruments).
The selectivity of the measurement wavelength .lamda. nm may be
conducted by a manual exchange of a wavelength-filter, a program
conversion of a measurement wavelength value or the like.
When the film tested is represented by an uniaxial or biaxial
refractive index ellipsoid, then its Rth(.lamda.) is calculate
according to the method mentioned below.
With the in-plane slow axis (determined by KOBRA 21ADH or WR) taken
as the inclination axis (rotation axis) of the film (in case where
the film has no slow axis, the rotation axis of the film may be in
any in-plane direction of the film), Re(.lamda.) of the film is
measured at 6 points in all thereof, up to +50.degree. relative to
the normal direction of the film at intervals of 10.degree., by
applying a light having a wavelength of .lamda. nm from the
inclined direction of the film.
With the in-plane slow axis from the normal direction taken as the
rotation axis thereof, when the film has a zero retardation value
at a certain inclination angle, then the symbol of the retardation
value of the film at an inclination angle larger than that
inclination angle is changed to a negative one, and then applied to
KOBRA 21ADH or WR for computation.
With the slow axis taken as the inclination axis (rotation axis)
(in case where the film has no slow axis, the rotation axis of the
film may be in any in-plane direction of the film), the retardation
values of the film are measured in any inclined two directions; and
based on the data and the mean refractive index and the inputted
film thickness, Rth may be calculated according to the following
formulae (1) and (2):
.times..times..times..times..theta..times..times..times..times..function.-
.function..function..theta..times..times..function..function..function..th-
eta..times..times..times..function..function..theta..times..times..times..-
times..times. ##EQU00001## wherein Re(.theta.) means the
retardation value of the film in the direction inclined by an angle
.theta. from the normal direction; nx means the in-plane refractive
index of the film in the slow axis direction; ny means the in-plane
refractive index of the film in the direction vertical to nx; nz
means the refractive index of the film vertical to nx and ny; and d
is a thickness of the film.
When the film to be tested could not be represented by a monoaxial
or biaxial index ellipsoid, or that is, when the film does not have
an optical axis, then its Rth(.lamda.) may be calculated according
to the method mentioned below.
With the in-plane slow axis (determined by KOBRA 21ADH or WR) taken
as the inclination axis (rotation axis) of the film, Re(.lamda.) of
the film is measured at 11 points in all thereof, from -50.degree.
to +50.degree. relative to the normal direction of the film at
intervals of 10.degree., by applying a light having a wavelength of
.lamda. nm from the inclined direction of the film. Based on the
thus-determined retardation data of Re(7), the mean refractive
index and the inputted film thickness, Rth(.lamda.) of the film is
calculated with KOBRA 21ADH or WR.
The mean refractive index may be used values described in catalogs
for various types of optical films. When the mean refractive index
has not known, it may be measured with Abbe refractometer. The mean
refractive index for major optical film is described below:
cellulose acetate (1.48), cycloolefin polymer (1.52), polycarbonate
(1.59), polymethylmethacrylate (1.49), polystyrene (1.59). The mean
refractive index and the film thickness are inputted in KOBRA 21ADH
or WR, nx, ny and nz are calculated therewith. From the
thus-calculated data of nx, ny and nz, Nz=(nx-nz)/(nx-ny) is
further calculated. (Measurement of Tilt Angle)
It is difficult to accurately and directly measure .theta.1, which
is a tilt angle at a surface of an optically-anisotropic film (an
angle between the physical symmetric axis of a discotic or rod-like
liquid-crystal molecule in the optically-anisotropic film and an
interface of the layer), and .theta.2, which is a tilt angle at
another surface of the optically-anisotropic film. Therefore, in
this description, .theta.1 and .theta.2 are calculated as follows:
This method could not accurately express the actual alignment
state, but may be helpful as a means for indicating the relative
relationship of some optical characteristics of an optical
film.
In this method, the following two points are assumed for
facilitating the calculation, and the tilt angles at two interfaces
of an optically-anisotropic film are determined.
1. It is assumed that an optically-anisotropic film is a
multi-layered structure that comprises a layer containing discotic
or rod-like compound(s). It is further assumed that the minimum
unit layer constituting the structure (on the assumption that the
tilt angle of the discotic or rod-like molecule is uniform inside
the layer) is an optically-monoaxial layer.
2. It is assumed that the tilt angle in each layer varies
monotonously as a linear function in the direction of the thickness
of an optically-anisotropic layer.
A concrete method for calculation is as follows: (1) In a plane in
which the tilt angle in each layer monotonously varies as a linear
function in the direction of the thickness of an
optically-anisotropic film, the incident angle of light to be
applied to the optically-anisotropic film is varied, and the
retardation is measured at three or more angles. For simplifying
the measurement and the calculation, it is desirable that the
retardation is measured at three angles of -40.degree., 0.degree.
and +40.degree. relative to the normal direction to the
optically-anisotropic film of being at an angle of 0.degree.. For
the measurement, for example, used are KOBRA-21ADH and KOBRA-WR (by
Oji Scientific Instruments), and transmission ellipsometers AEP-100
(by Shimadzu), M150 and M520 (by Nippon Bunko) and ABR10A (by
Uniopto). (2) In the above model, the refractive index of each
layer for normal light is represented by n0; the refractive index
thereof for abnormal light is by ne (ne is the same in all layers
as well as n0); and the overall thickness of the multi-layer
structure is represented by d. On the assumption that the tilting
direction in each layer and the monoaxial optical axis direction of
the layer are the same, the tilt angle .theta.1 in one face of the
optically-anisotropic layer and the tilt angle .theta.2 in the
other face thereof are fitted as variables in order that the
calculated data of the angle dependence of the retardation of the
optically-anisotropic layer could be the same as the found data
thereof, and .theta.1 and .theta.2 are thus calculated.
In this, n0 and ne may be those known in literature and catalogues.
When they are unknown, they may be measured with an Abbe's
refractometer. The thickness of the optically-anisotropic film may
be measured with an optical interference thickness gauge or on a
photograph showing the cross section of the layer taken by a
scanning electronic microscope.
It is also noted that, in the description, the expression of "the
number of carbon atoms in a group" means the number of all carbon
atoms in the group if there is no negative notation, and if the
group has any substituent, carbon atoms in the substituent are also
counted.
It is also noted that, in the description, the term "group" means
may have any substituent if there is no negative notation.
[Composition]
The composition of the invention comprises at least one liquid
crystal compound and at least one polymer comprising a
constitutional unit represented by the following formula (A) and a
constitutional unit derived from a monomer having a fluoroaliphatic
group. Hereinafter, the polymer may be referred to as "polymer used
in the invention".
The polymer used in the invention and the liquid crystalline
compound favorably used will be described below.
The polymer comprising a constitutional unit represented by the
following formula (A) and a constitutional unit derived from a
monomer having a fluoroaliphatic group contributes to aligning
liquid crystal molecules, particularly discotic liquid crystal
molecules, in a hybrid alignment state with a low mean tilt angle.
Furthermore, the mean tilt angle is hard to change on fluctuation
in temperature, and therefore, an optically anisotropic film and
the like having intended optical characteristics can be produced
stably by using the polymer.
(1) Constitutional Unit Represented by Formula (A)
##STR00018##
In the formula (A), Mp represents a trivalent group constituting a
polymer main chain fully or partially, L represents a single bond
or a divalent linking group, and X represents a substituted or
non-substituted aromatic condensed ring group.
In the formula (A), Mp represents a trivalent group, which
constitutes the main chain of the polymer fully or partially.
Preferred examples of the trivalent group represented by Mp in the
formula (A) include a substituted or non-substituted and linear or
branched alkylene group having from 2 to 20 carbon atoms (without
carbon atoms in the substituent, hereinafter the same for the
carbon numbers in Mp) (such as an ethylene group, a propylene
group, a methylethylene group, a butylene group and a hexylene
group), a substituted or non-substituted cyclic alkylene group
having from 3 to 10 carbon atoms (such as a cyclopropylene group, a
cyclobutylene group and a cyclohexylene group), a substituted or
non-substituted vinylene group, a substituted or non-substituted
cyclic vinylene group, a substituted or non-substituted phenylene
group, a group containing an oxygen atom (such as groups containing
an ether group, an acetal group, an ester group, a carbonate group
or the like), a group containing a nitrogen atom (such as groups
containing an amino group, an imino group, an amide group, a
urethane group, a ureido group, an imide group, an imidazole group,
an oxazole group, a pyrrole group, an anilide group, a maleimide
group or the like), a group containing a sulfur atom (such as
groups containing a sulfide group, a sulfone group, a thiophene
group or the like), a group containing a phosphorous atom (such as
groups containing a phosphine group, a phosphate ester group or the
like), a group containing a silicon atom (such as groups containing
a siloxane group or the like), and a group formed by bonding two or
more of these groups, in which a hydrogen atom contained in the
group is substituted with a group represented by -L-X, more
preferred examples of the group represented by Mp include a
substituted or non-substituted ethylene group, a substituted or
non-substituted methylethylene group, a substituted or
non-substituted cyclohexylene group and a substituted or
non-substituted vinylene group, in which a hydrogen atom contained
in the group is substituted with a group represented by -L-X,
further preferred examples of the group represented by Mp include a
substituted or non-substituted ethylene group, a substituted or
non-substituted methylethylene group and a substituted or
non-substituted vinylene group, in which a hydrogen atom contained
in the group is substituted with a group represented by -L-X, and
particularly preferred examples of the group represented by Mp
include a substituted or non-substituted ethylene group and a
substituted or non-substituted methylethylene group, in which a
hydrogen atom contained in the group is substituted with a group
represented by -L-X. Specifically, the groups (Mp-1) and (Mp-2)
shown below are preferred as the group represented by Mp.
Specific examples of the group represented by Mp include the groups
(Mp-1) to (Mp-19) shown below, but Mp is not limited to these
groups. In the formulae of (Mp-1) to (Mp-19), the symbol * shows
the position, to which the group L is bonded.
##STR00019## ##STR00020##
Preferred examples of the divalent linking group represented by L
in the formula (A) include an alkylene group having from 1 to 20
carbon atoms (such as a methylene group, an ethylene group, a
propylene group, a butylene group and an isopropylene group), an
alkenylene group having from 2 to 20 carbon atoms (such as a
vinylene group and a butene group), --O--, --NR.sup.a1--, --S--,
--PR.sup.a2--, --Si(R.sup.a3)(R.sup.a4)--, --C(.dbd.O)--,
--C(.dbd.O)O--, --C(.dbd.O)NR.sup.a5--, --OC(.dbd.O)O--,
--OC(.dbd.O)NR.sup.a6--, --NR.sup.a7C(.dbd.O)NR.sup.a8--,
--(--O).sub.2CH-- and a group formed by bonding two or more of
these groups.
R.sup.a1 to R.sup.a8 each represents a substituent, which may be
substituted, and examples thereof include a hydrogen atom, a
halogen atom, an alkyl group (including a cycloalkyl group having
one or more cyclic structure, such as a monocycloalkyl group and a
bicycloalkyl group), an alkenyl group (including a cycloalkenyl
group and a bicycloalkenyl group), an alkynyl group, a cyano group,
a hydroxyl group, a nitro group, a carboxyl group, an alkoxy group,
a silyloxy group, an acyloxy group, an alkoxycarbonyloxy group, an
amino group (except for an anilino group), an acylamino group, an
aminocarbonylamino group, an alkoxycarbonylamino group, a mercapto
group, an alkylthio group, a sulfamoyl group, a sulfo group, an
alkylsulfinyl group, an alkylsulfonyl group, an acyl group, an
alkoxycarbonyl group, an imide group, a phosphino group, a
phosphinyl group, a phosphinyloxy group, a phosphinylamino group
and a silyl group, and a hydrogen atom and an alkyl group are
preferred.
More preferred examples of the divalent linking group represented
by L in the formula (A) include --O--, NR.sup.a11-- (wherein
R.sup.a11 represents a hydrogen atom or an aliphatic hydrocarbon
group having from 1 to 10 carbon atoms), --S--, --C(.dbd.O)--,
--S(.dbd.O).sub.2--, a substituted or non-substituted alkylene
group having from 1 to 20 carbon atoms and a group formed by
bonding two or more of these groups. Particularly preferred
examples of the divalent linking group represented by L include
--C(.dbd.O)O--, --OC(.dbd.O)--, --O--, --OC(.dbd.O)O--,
--C(.dbd.O)NH--, --NHC(.dbd.O)--, --C(.dbd.O)O(CH.sub.2).sub.mO--,
--(CH.sub.2).sub.m-- and a group formed by bonding two or more of
these groups.
The number m represents an integer of from 1 to 20. The number m is
preferably from 1 to 16, more preferably from 2 to 12, and further
preferably from 2 to 6, for controlling properly the degree of
freedom of X. By properly controlling the degree of freedom of X,
the mutual interaction with the liquid crystal to be oriented is
increased, and the orientation of X can be properly controlled,
whereby the mean tilt angle can be controlled more effectively.
The linking groups (L-1) to (L-7) shown below are also preferred as
the divalent linking group represented by L. In the formulae of
(L-1) to (L-7), the symbol * shows the position, to which the group
Mp is bonded, and m represents an integer of from 1 to 20 and has
the same meaning as m mentioned above with the same preferred
ranges.
##STR00021##
In the case where Mp in the formula (A) represents (Mp-1) or
(Mp-2), preferred examples of the divalent linking group L include
--O--, --NR.sup.a11-- (wherein R.sup.a11 represents a hydrogen atom
or an aliphatic hydrocarbon group having from 1 to 10 carbon
atoms), --S--, --C(.dbd.O)--, --S(.dbd.O).sub.2--, a substituted or
non-substituted alkylene group having from 1 to 20 carbon atoms and
a group formed by bonding two or more of these groups, and more
preferred examples thereof include --O--, --C(.dbd.O)O--,
--C(.dbd.O)NH-- and a divalent group formed by bonding one or more
of these groups and an alkylene group, for example, the groups
(L-1), (L-2) and (L-3), (L-6) above.
The number of rings in the substituted or non-substituted aromatic
condensed ring group represented by X in the formula (A) is not
particularly limited, and a group formed by condensing from 2 to 5
rings is preferred. The group includes not only a hydrocarbon
aromatic condensed ring containing only carbon atoms as the atoms
constituting the ring, but also an aromatic condensed ring formed
by condensing heterocyclic rings containing heteroatoms as the
atoms constituting the ring. Preferred examples of the group
represented by X include a substituted or non-substituted indenyl
group having from 5 to 30 carbon atoms (such as a methylindenyl
group, a methoxyindenyl group and an indenyl group substituted with
a hetero atom, e.g., a benzofuranyl group, a thionaphthenyl group,
an indolenyl group, an indazolenyl group, a benzimidazolenyl group,
a benzotriazolenyl group and a 1-pyrazolepyrazinyl group), a
substituted or non-substituted naphthyl group having from 6 to 30
carbon atoms (such as a methylnaphthyl group, a cyanonaphthyl
group, a fluoronaphthyl group, a bromonaphthyl group and a naphthyl
group substituted with a hetero atom, e.g., a quinolyl group, an
isoquinolyl group, a quinozolyl group, a quinoxalyl group, a
6,7-pyridopyridazinyl group, a benzotetrazinyl group and a pteryl
group), a substituted or non-substituted fluorenyl group having
from 12 to 30 carbon atoms (such as a 2,7-dimethylfluorenyl group
and a fluorenyl group substituted with a hetero atom, e.g., a
carbazolyl group, a dibenzofuranyl group and a dibenzothiophenyl
group), an anthryl group (such as a 5-methylanthryl group and an
anthryl group substituted with a hetero atom, e.g., a xanthenyl
group, an acridinyl group and a phenadinyl group), a pyrenyl group,
a perylenyl group and a phenanthrenyl group.
More preferred examples of the group represented by X in the
formula (A) include a substituted or non-substituted indenyl group
having from 5 to 30 carbon atoms and a substituted or
non-substituted naphthyl group having from 6 to 30 carbon atoms,
further preferred examples thereof include a substituted or
non-substituted naphthyl group having from 10 to 30 carbon atoms,
and particularly preferred examples thereof include a substituted
or non-substituted naphthyl group having from 10 to 20 carbon
atoms.
For the compounds where L represents a single bond, --O--,
NR.sup.a11-- (wherein R.sup.a11 represents a hydrogen atom or an
aliphatic hydrocarbon group having from 1 to 10 carbon atoms),
--S--, --C(.dbd.O)--, --S(.dbd.O).sub.2-- or a group formed by
bonding two or more of these groups, X preferably represents a
substituted or non-substituted naphthyl group.
Specific preferred examples of the constituting unit represented by
the formula (A) include, but are not limited to, constitutional
units A-1 to A-34 below.
##STR00022## ##STR00023## ##STR00024## ##STR00025## (2)
Constitutional Unit Derived from Monomer Having Fluoroaliphatic
Group(s)
The polymer used in the invention has a constitutional unit derived
from a monomer having a fluoroaliphatic group(s) with the
constitutional unit represented by the formula (A). The unit is
preferably a unit represented by a formula (B) below. The formula
will be described in detail.
##STR00026##
In formula (B), Mp' represents a trivalent group forming a main
chain partially; L' represents a single bond or a bivalent linking
group; and Rf represents a substituent having at least one fluorine
atom therein.
In the formula, Mp' has the same meaning as that of Mp in formula
(A), and its preferred range is also same as that therein.
In the formula, L' preferably represents --O--, --NR.sup.a11--
(where R.sup.a11 represents a hydrogen atom, an aliphatic
hydrocarbon group having from 1 to 10 carbon atoms, or an aryl
group having from 6 to 20 carbon atoms), --S--, --C(.dbd.O)--,
--S(.dbd.O).sub.2, and a substituted or non-substituted alkylene
group having from 1 to 20 carbon atoms, and a group formed by
linking at least two of these.
Examples of the bivalent linking group formed by linking at least
two or the above groups include --C(.dbd.O)--, --OC(.dbd.O)--,
--OC(.dbd.O)O--, --C(.dbd.O)NH--, --NHC(.dbd.O)--, and
--C(.dbd.O)O(CH.sub.2).sub.maO-- (where ma indicates an integer of
from 1 to 20).
In the unit of formula (B) wherein Mp' is (Mp-1) or (Mp-2), L' is
preferably a bivalent linking group selected from --O--,
--NR.sup.a11-- (where R.sup.a11 represents a hydrogen atom, or an
aliphatic hydrocarbon group having from 1 to 10 carbon atoms),
--S--, --C(.dbd.O)--, --S(.dbd.O).sub.2, and a substituted or
non-substituted alkylene group having from 1 to 20 carbon atoms,
and a group formed by linking at least two of these; more
preferably a bivalent linking group selected from --O--,
--C(.dbd.O)O--, and --C(.dbd.O)NH--, and a group of a combination
of at least one of these groups with an alkylene group (e.g.,
(L-1), (L-2), (L-3)).
Preferred examples of Rf include an aliphatic hydrocarbon group
having from 1 to 30 carbon atoms and substituted with at least one
fluorine atom (e.g., trifluoroethyl, perfluorohexylethyl,
perfluorohexylpropyl, perfluorobutylethyl, and
perfluorooctylethyl). Also preferably, Rf has a group CF.sub.3 or
CF.sub.2H, more preferably a group CF.sub.3, at its terminal.
More preferably, Rf is an alkyl group having a group CF.sub.3 at
its terminal, or an alkyl group having CF.sub.2H at its terminal.
The alkyl group having CF.sub.3 at its terminal is an alkyl group
in which a part or all of the hydrogen atoms constituting the alkyl
group are substituted with a fluorine atom. Preferably, at least
50% of hydrogen atoms constituting the alkyl group having CF.sub.3
at its terminal are substituted with a fluorine atom; more
preferably at least 60% thereof are substituted; and even more
preferably at least 70% thereof are substituted. The remaining
hydrogen atoms may be substituted with the substituent in the
substituent group D given hereinunder.
The alkyl group having a group CF.sub.2H at its terminal is an
alkyl group in which a part or all of the hydrogen atoms
constituting the alkyl group are substituted with a fluorine atom.
Preferably, at least 50% of the hydrogen atoms constituting the
alkyl group having CF.sub.2H at its terminal are substituted with a
fluorine atom; more preferably at least 60% thereof are
substituted; and even more preferably at least 70% thereof are
substituted. The remaining hydrogen atoms may be substituted with
the substituent in the substituent group D given hereinunder.
Substituent Group D:
In this description, Substituent Group D includes an alkyl group
(preferably having from 1 to 20 carbon atoms, more preferably from
1 to 12 carbon atoms, even more preferably from 1 to 8 carbon
atoms, such as methyl group, ethyl group, isopropyl group,
tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group,
cyclopropyl group, cyclopentyl group, cyclohexyl group), an alkenyl
group (preferably having from 2 to 20 carbon atoms, more preferably
from 2 to 12 carbon atoms, even more preferably from 2 to 8 carbon
atoms, such as vinyl group, allyl group, 2-butenyl group,
3-pentenyl group), an alkynyl group (preferably having from 2 to 20
carbon atom, more preferably from 2 to 12 carbon atoms, even more
preferably from 2 to 8 carbon atoms, such as propargyl group,
3-pentynyl group), an aryl group (preferably having from 6 to 30
carbon atoms, more preferably 6 to 20 carbon atoms, even more
preferably from 6 to 12 carbon atoms, such as phenyl group,
p-methylphenyl group, naphthyl group), a substituted or
non-substituted amino group (preferably having from 0 to 20 carbon
atoms, more preferably from 0 to 10 carbon atoms, even more
preferably from 0 to 6 carbon atoms, such as non-substituted amino
group, methylamino group, dimethylamino group, diethylamino group,
dibenzylamino group), an alkoxy group (preferably having from 1 to
20 carbon atoms, more preferably from 1 to 12 carbon atoms, even
more preferably from 1 to 8 carbon atoms, such as methoxy group,
ethoxy group, butoxy group), an aryloxy group (preferably having
from 6 to 20 carbon atoms, more preferably from 6 to 16 carbon
atoms, even more preferably from 6 to 12 carbon atoms, such as
phenyloxy group, 2-naphthyloxy group), an acyl group (preferably
having from 1 to 20 carbon atoms, more preferably from 1 to 16
carbon atoms, even more preferably from 1 to 12 carbon atoms, such
as acetyl group, benzoyl group, formyl group, pivaloyl group), an
alkoxycarbonyl group (preferably having from 2 to 20 carbon atoms,
more preferably from 2 to 16 carbon atoms, even more preferably
from 2 to 12 carbon atoms, such as methoxycarbonyl group,
ethoxycarbonyl group), an aryloxycarbonyl group (preferably having
from 7 to 20 carbon atoms, more preferably from 7 to 16 carbon
atoms, even more preferably from 7 to 10 carbon atoms, such as
phenyloxycarbonyl group), an acyloxy group (preferably having from
2 to 20 carbon atoms, more preferably from 2 to 16 carbon atoms,
even more preferably from 2 to 10 carbon atoms, such as acetoxy
group, benzoyloxy group), an acylamino group (preferably having
from 2 to 20 carbon atoms, more preferably from 2 to 16 carbon
atoms, even more preferably from 2 to 10 carbon atoms, such as
acetylamino group, benzoylamino group), an alkoxycarbonylamino
group (preferably having from 2 to 20 carbon atoms, more preferably
from 2 to 16 carbon atoms, even more preferably from 2 to 12 carbon
atoms, such as methoxycarbonylamino group), an aryloxycarbonylamino
group (preferably having from 7 to 20 carbon atoms, more preferably
from 7 to 16 carbon atoms, even more preferably from 7 to 12 carbon
atoms, such as phenyloxycarbonylamino group), a sulfonylamino group
(preferably having from 1 to 20 carbon atoms, more preferably from
1 to 16 carbon atoms, even more preferably from 1 to 12 carbon
atoms, such as methanesulfonylamino group, benzenesulfonylamino
group), a sulfamoyl group (preferably having from 0 to 20 carbon
atoms, more preferably from 0 to 16 carbon atoms, even more
preferably from 0 to 12 carbon atoms, such as sulfamoyl group,
methylsulfamoyl group, dimethylsulfamoyl group, phenylsulfamoyl
group), a carbamoyl group (preferably having from 1 to 20 carbon
atoms, more preferably from 1 to 16 carbon atoms, even more
preferably from 1 to 12 carbon atoms, such as non-substituted
carbamoyl group, methylcarbamoyl group, diethylcarbamoyl group,
phenylcarbamoyl group), an alkylthio group (preferably having from
1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms,
even more preferably from 1 to 12 carbon atoms, such as methylthio
group, ethylthio group), an arylthio group (preferably having from
6 to 20 carbon atoms, more preferably from 6 to 16 carbon atoms,
even more preferably from 6 to 12 carbon atoms, such as phenylthio
group), a sulfonyl group (preferably having from 1 to 20 carbon
atoms, more preferably from 1 to 16 carbon atoms, even more
preferably from 1 to 12 carbon atoms, such as mesyl group, tosyl
group), a sulfinyl group (preferably having from 1 to 20 carbon
atoms, more preferably from 1 to 16 carbon atoms, even more
preferably from 1 to 12 carbon atoms, such as methanesulfinyl
group, benzenesulfinyl group), an ureido group (preferably having
from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon
atoms, even more preferably from 1 to 12 carbon atoms, such as
non-substituted ureido group, methylureido group, phenylureido
group), a phosphoramido group (preferably having from 1 to 20
carbon atoms, more preferably from 1 to 16 carbon atoms, even more
preferably from 1 to 12 carbon atoms, such as diethylphosphoramido
group, phenylphosphoramido group), hydroxyl group, a mercapto
group, a halogen atom (e.g., fluorine atom, chlorine atom, bromine
atom, iodine atom), a cyano group, a sulfo group, a carboxyl group,
a nitro group, a hydroxamic acid group, a sulfino group, a
hydrazino group, an imino group, a heterocyclic group (preferably
having from 1 to 30 carbon atoms, more preferably from 1 to 12
carbon atoms, and having a hetero atom such as a nitrogen atom, an
oxygen atom or a sulfur atom, for example, imidazolyl group,
pyridyl group, quinolyl group, furyl group, piperidyl group,
morpholino group, benzoxazolyl group, benzimidazolyl group,
benzothiazolyl group), a silyl group (preferably having from 3 to
40 carbon atoms, more preferably from 3 to 30 carbon atoms, even
more preferably from 3 to 24 carbon atoms, such as trimethylsilyl
group, triphenylsilyl group). These substituents may be further
substituted with any of these substituents. When the substituent
has two or more substituents, then they may be the same or
different. If possible, the substituents may bond to each other to
form a ring.
Examples of the alkyl group having a group CF.sub.3 at its terminal
and the alkyl group having a group CF.sub.2H at its terminal are
shown below. n-C.sub.8F.sub.17-- R1 n-C.sub.6F.sub.13-- R2
n-C.sub.4F.sub.9-- R3 n-C.sub.8F.sub.17--(CH.sub.2).sub.2-- R4
n-C.sub.6F.sub.13--(CH.sub.2).sub.2-- R5
n-C.sub.4F.sub.9--(CH.sub.2).sub.2 R6 H--(CF.sub.2).sub.8-- R7
H--(CF.sub.2).sub.6-- R8 H--(CF.sub.2).sub.4-- R9
H--(CF.sub.2).sub.8--(CH.sub.2)-- R10
H--(CF.sub.2).sub.6--(CH.sub.2)-- R11
H--(CF.sub.2).sub.4--(CH.sub.2)-- R12
n-C.sub.4F.sub.9--(CH.sub.2).sub.2--O--(CH.sub.2).sub.3--O-- R13
n-C.sub.5F.sub.13--(CH.sub.2).sub.2--O-- R14
n-C.sub.4F.sub.9--(CH.sub.2).sub.2--O-- R15
Specific examples of preferred repetitive units derived from the
monomer having a fluoroaliphatic group(s) include, but are not
limited to, those shown below.
##STR00027## ##STR00028##
The polymer for use in the invention may comprise a repetitive unit
having a structure of formula (A), and repetitive unit derived from
a monomer having a fluoroaliphatic group(s), and in addition to
these, may further comprise any other constitutive unit derived
from a monomer copolymerizable with the monomers to form these
constitutive units.
The copolymerizable monomer is not specifically defined. Preferred
monomers are, for example, monomers to constitute hydrocarbon
polymers (e.g., polyethylene, polypropylene, polystyrene,
polymaleinimide, polyacrylic acid, polyacrylate, polyacrylamide,
polyacrylanilide), polyethers, polyesters, polycarbonates,
polyamides, polyamic acids, polyimides, polyurethanes and
polyureides. These may be in the polymer for improving the
solubility of the polymer in solvent and for preventing aggregation
of the polymer.
Preferably, the backbone chain structure of the comonomer is the
same as the group of formula (A).
Specific examples of the copolymerizable constitutive units are
mentioned below, to which, however, the invention should not be
limited. Especially preferred are (C-2), (C-3), (C-10), (C-11),
(C-12) and (C-19); and more preferred are (C-11) and (C-19).
##STR00029## ##STR00030## ##STR00031##
The content of the group of formula (A) in the polymer for use in
the invention is preferably from 1 to 90% by mass, more preferably
from 3 to 80% by mass.
The content of the repetitive unit derived from a monomer having a
fluoroaliphatic group(s) (preferably the group of formula (B)) in
the polymer for use in the invention is from 5 to 90% by mass, more
preferably from 10 to 80% by mass.
The content of the other constitutive unit than the above-mentioned
two in the polymer is preferably at most 60% by mass, more
preferably at most 50% by mass.
The copolymer may be a random copolymer where the constitutive
units are irregularly ordered, or a block copolymer where they are
regularly ordered. In the block copolymer, the constitutive units
may be ordered in any manner, and the same constitutive component
may be ordered twice or more.
One or more different types of the group of formula (A) and the
group of formula (B) may constitute the copolymer. For the polymers
comprising two or more units represented by formula (A), it is
preferred that the units are same as each other in terms of the
condensed ring framework and are different from each other in terms
of the substituent of the condensed ring (for example, one may have
a non-substituted condensed ring group, and another may have a
substituted same condensed ring group). In the copolymer that
comprises two or more different types of the groups, the content of
the constitutive groups is the overall content thereof.
Regarding the molecular weight range of the polymer for use in the
invention, the number-average molecular weight (Mn) of the polymer
is preferably from 1000 to 1,000,000, more preferably from 3000 to
200,000, even more preferably from 5000 to 100,000. The molecular
weight distribution (Mw/Mn, Mw is weight-average molecular weight)
of the polymer for use in the invention is preferably from 1 to 4,
more preferably from 1.5 to 4.
The amount of the polymer to be in the composition of the invention
is preferably from 0.001 to 10% by mass of the liquid-crystal
compound therein, more preferably from 0.1 to 5.0% by mass, even
more preferably from 0.5 to 2.5% by mass.
Preferred examples of the polymer to be used in the composition of
the invention are shown in Table 1 below.
TABLE-US-00002 TABLE 1 Constitution Number- of Average Molecular
Repetitive Copolymerization Molecular Weight Units of Ratio Weight
Distribution Polymer (% by mass) (Mn) (Mw/Mn) AD-1 A-6/B-3 60/40
12000 2.25 AD-2 A-6/B-3 62.5/37.5 10100 2.01 AD-3 A-6/B-3 65/35
12400 2.22 AD-4 A-6/B-3 67.5/32.5 11100 2.03 AD-5 A-6/B-3 70/30
10800 2.14 AD-6 A-6/B-3/B-1 55/22.5/22.5 10000 2.01 AD-7
A-6/B-3/B-1 60/20/20 10900 2.04 AD-8 A-6/B-3/B-1 65/17.5/17.5 10400
2.09 AD-9 A-6/B-3/B-1 60/20/20 14300 2.22 AD-10 A-6/B-3/B-1
60/20/20 18400 2.41 AD-11 A-6/B-3/B-1 60/20/20 7400 1.87 AD-12
A-6/B-3/C-11 33.75/32.5/33.75 11000 2.14 AD-13 A-6/B-3/C-11
17.0/32.5/50.5 12700 2.18 AD-14 A-6/B-3/C-19 15/40/45 16700 3.00
AD-15 A-6/A-9/B-3 57/3/40 14700 2.98 AD-16 A-6/A-7/B-3 30/30/40
16300 2.93 AD-17 A-6/A-8/B-3 30/30/40 13000 2.30 AD-18 A-6/A-9/B-3
40/20/40 12500 2.40
The polymer for use in the invention may be produced according to
any method. The polymer for use in the invention may be produced
through addition, condensation or substitution or a combination of
any of these. Not specifically defined, when the polymer for use in
the invention has an ethylenic repetitive unit, then it is
desirable that the polymer is produced through radical
polymerization of an ethylenic unsaturated compound corresponding
to the repetitive unit, as the method is simple.
Liquid Crystal Compound
The liquid crystal compound used in the invention is not
particularly limited, a compound exhibiting discotic liquid
crystallinity (a discotic liquid crystal compound) is preferred,
and a compound exhibiting a discotic nematic phase is more
preferred. Examples of the liquid crystal compound to be used in
the invention include any compounds represented by formula
(DI).
[Compound of Formula (DI)]
The compound represented by formula to be used in the invention is
preferably a discotic liquid crystal compound, and more preferably,
exhibits a discotic nematic phase.
##STR00032##
In formula (DI), Y.sup.11, Y.sup.12 and Y.sup.13 each independently
represent a methine group or a nitrogen atom. L.sup.1, L.sup.2 and
L.sup.3 each independently represent a single bond or a bivalent
linking group. H.sup.1, H.sup.2 and H.sup.3 each independently
represent the following formula (DI-A) or (DI-B). R.sup.1, R.sup.2
and R.sup.3 each independently represent the following formula
(DI-R).
In formula (DI), Y.sup.11, Y.sup.12 and Y.sup.13 each independently
represent a methine group or a nitrogen atom. When each of
Y.sup.11, Y.sup.12 and Y.sup.13 each is a methine group, the
hydrogen atom of the methine group may be substituted with a
substituent. Examples of the substituent of the methine group
include an alkyl group, an alkoxy group, an aryloxy group, an acyl
group, an alkoxycarbonyl group, an acyloxy group, an acylamino
group, an alkoxycarbonylamino group, an alkylthio group, an
arylthio group, a halogen atom, and a cyano group. Of those,
preferred are an alkyl group, an alkoxy group, an alkoxycarbonyl
group, an acyloxy group, a halogen atom and a cyano group; more
preferred are an alkyl group having from 1 to 12 carbon atoms (the
term "carbon atoms" means hydrocarbons in a substituent, and the
terms appearing in the description of the substituent of the
discotic liquid crystal compound have the same meaning), an alkoxy
group having from 1 to 12 carbon atoms, an alkoxycarbonyl group
having from 2 to 12 carbon atoms, an acyloxy group having from 2 to
12 carbon atoms, a halogen atom and a cyano group.
Preferably, Y.sup.11, Y.sup.12 and Y.sup.13 are all methine groups,
more preferably non-substituted methine groups.
In formula (DI), L.sup.1, L.sup.2 and L.sup.3 each independently
represent a single bond or a bivalent linking group. The bivalent
linking group is preferably selected from --O--, --S--,
--C(.dbd.O)--, --NR.sup.7--, --CH.dbd.CH--, --C.ident.C--, a
bivalent cyclic group, and their combinations. R.sup.7 represents
an alkyl group having from 1 to 7 carbon atoms, or a hydrogen atom,
preferably an alkyl group having from 1 to 4 carbon atoms, or a
hydrogen atom, more preferably a methyl, an ethyl or a hydrogen
atom, even more preferably a hydrogen atom.
The bivalent cyclic group for L.sup.1, L.sup.2 and L.sup.3 is
preferably a 5-membered, 6-membered or 7-membered group, more
preferably a 5-membered or 6-membered group, even more preferably a
6-membered group. The ring in the cyclic group may be a condensed
ring. However, a monocyclic ring is preferred to a condensed ring
for it. The ring in the cyclic ring may be any of an aromatic ring,
an aliphatic ring, or a hetero ring. Examples of the aromatic ring
are a benzene ring and a naphthalene ring. An example of the
aliphatic ring is a cyclohexane ring. Examples of the hetero ring
are a pyridine ring and a pyrimidine ring. Preferably, the cyclic
group contains an aromatic ring and a hetero ring.
Of the bivalent cyclic group, the benzene ring-having cyclic group
is preferably a 1,4-phenylene group. The naphthalene ring-having
cyclic group is preferably a naphthalene-1,5-diyl group or a
naphthalene-2,6-diyl group. The pyridine ring-having cyclic group
is preferably a pyridine-2,5-diyl group. The pyrimidine ring-having
cyclic group is preferably a pyrimidin-2,5-diyl group.
The bivalent cyclic group for L.sup.1, L.sup.2 and L.sup.3 may have
a substituent. Examples of the substituent are a halogen atom, a
cyano group, a nitro group, an alkyl group having from 1 to 16
carbon atoms, an alkenyl group having from 2 to 16 carbon atoms, an
alkynyl group having from 2 to 16 carbon atoms, a halogen
atom-substituted alkyl group having from 1 to 16 carbon atoms, an
alkoxy group having from 1 to 16 carbon atoms, an acyl group having
from 2 to 16 carbon atoms, an alkylthio group having from 1 to 16
carbon atoms, an acyloxy group having from 2 to 16 carbon atoms, an
alkoxycarbonyl group having from 2 to 16 carbon atoms, a carbamoyl
group, an alkyl group-substituted carbamoyl group having from 2 to
16 carbon atoms, and an acylamino group having from 2 to 16 carbon
atoms.
In the formula, L.sup.1, L.sup.2 and L.sup.3 are preferably a
single bond, *--O--CO--, *--CO--O--, *--CH.ident.CH--, *-"bivalent
cyclic group"-, *--O--CO-"bivalent cyclic group"-,
*--CO--O-"bivalent cyclic group"-, *--CH.dbd.CH-"bivalent cyclic
group"-, "bivalent cyclic group"-CO--O--, *-"bivalent cyclic
group"-O--CO--, *-"bivalent cyclic group"-CO--O--, *-"bivalent
cyclic group"-CH.dbd.CH--, or *-"bivalent cyclic
group"-C.ident.C--. More preferably, they are a single bond,
*--CH.dbd.CH--, *--CH.dbd.CH-"bivalent cyclic group"-- or
*--C.ident.C-"bivalent cyclic group"-, even more preferably a
single bond. In the examples, "*" indicates the position at which
the group bonds to the 6-membered ring of formula (DI) that
contains Y.sup.11, Y.sup.12 and Y.sup.13.
In formula (DI), H.sup.1, H.sup.2 and H.sup.3 each independently
represent the following formula (DI-A) or (DI-B):
##STR00033##
In formula (DI-A), YA.sup.1 and YA.sup.2 each independently
represent a methine group or a nitrogen atom. Preferably, at least
one of YA.sup.1 and YA.sup.2 is a nitrogen atom, more preferably
they are both nitrogen atoms. XA represents an oxygen atom, a
sulfur atom, a methylene group or an imino group. XA is preferably
an oxygen atom. * indicates the position at which the formula bonds
to any of L.sup.1 to L.sup.3; and ** indicates the position at
which the formula bonds to any of R.sup.1 to R.sup.3.
##STR00034##
In formula (DI-B), YB.sup.1 and YB.sup.2 each independently
represent a methine group or a nitrogen atom. Preferably, at least
one of YB.sup.1 and YB.sup.2 is a nitrogen atom, more preferably
they are both nitrogen atoms. XB represents an oxygen atom, a
sulfur atom, a methylene group or an imino group. XB is preferably
an oxygen atom. * indicates the position at which the formula bonds
to any of L.sup.1 to L.sup.3; and ** indicates the position at
which the formula bonds to any of R.sup.1 to R.sup.3.
In the formula, R.sup.1, R.sup.2 and R.sup.3 each independently
represent the following formula (DI-R):
*-(-L.sup.21-F.sup.1).sub.n1-L.sup.22-L.sup.23-Q.sup.1 (DI-R)
In formula (DI-R), * indicates the position at which the formula
bonds to H.sup.1, H.sup.2 or H.sup.3 in formula (DI). F.sup.1
represents a bivalent linking group having at least one cyclic
structure. L.sup.21 represents a single bond or a bivalent linking
group. When L.sup.21 is a bivalent linking group, it is preferably
selected from a group consisting of --O--, --S--, --C(.dbd.O)--,
--NR.sup.7--, --CH.dbd.CH--, --C.ident.C--, and their combination.
R.sup.7 represents an alkyl group having from 1 to 7 carbon atoms,
or a hydrogen atom, preferably an alkyl group having from 1 to 4
carbon atoms, or a hydrogen atom, more preferably a methyl group,
an ethyl group or a hydrogen atom, even more preferably a hydrogen
atom.
In the formula, L.sup.21 is preferably a single bond, **--O--CO--,
**--CO--O--, **--CH.dbd.CH-- or **--C.ident.C-- (in which **
indicates the left side of L.sup.21 in formula (DI-R)). More
preferably it is a single bond.
In formula (DI-R), F.sup.1 represents a bivalent cyclic linking
group having at least one cyclic structure. The cyclic structure is
preferably a 5-membered ring, a 6-membered ring, or a 7-membered
ring, more preferably a 5-membered ring or a 6-membered ring, even
more preferably a 6-membered ring. The cyclic structure may be a
condensed ring. However, a monocyclic ring is preferred to a
condensed ring for it. The ring in the cyclic ring may be any of an
aromatic ring, an aliphatic ring, or a hetero ring. Examples of the
aromatic ring are a benzene ring, a naphthalene ring, an anthracene
ring, a phenanthrene ring. An example of the aliphatic ring is a
cyclohexane ring. Examples of the hetero ring are a pyridine ring
and a pyrimidine ring.
The benzene ring-having group for F.sup.1 is preferably a
1,4-phenylene group or a 1,3-phenylene group. The naphthalene
ring-having group is preferably a naphthalene-1,4-diyl group, a
naphthalene-1,5-diyl group, a naphthalene-1,6-diyl group, a
naphthalene-2,5-diyl group, a naphthalene-2,6-diyl group, or a
naphthalene-2,7-diyl group. The cyclohexane ring-having group is
preferably a 1,4-cyclohexylene group. The pyridine ring-having
group is preferably a pyridine-2,5-diyl group. The pyrimidine
ring-having group is preferably a pyrimidin-2,5-diyl group. More
preferably, F.sup.1 is a 1,4-phenylene group, a 1,3-phenylene
group, a naphthalene-2,6-diyl group, or a 1,4-cyclohexylene
group.
In the formula, F.sup.1 may have a substituent. Examples of the
substituent are a halogen atom (e.g., fluorine atom, chlorine atom,
bromine atom, iodine atom), a cyano group, a nitro group, an alkyl
group having from 1 to 16 carbon atoms, an alkenyl group having
from 1 to 16 carbon atoms, an alkynyl group having from 2 to 16
carbon atoms, a halogen atom-substituted alkyl group having from 1
to 16 carbon atoms, an alkoxy group having from 1 to 16 carbon
atoms, an acyl group having from 2 to 16 carbon atoms, an alkylthio
group having from 1 to 16 carbon atoms, an acyloxy group having
from 2 to 16 carbon atoms, an alkoxycarbonyl group having from 2 to
16 carbon atoms, a carbamoyl group, an alkyl group-substituted
carbamoyl group having from 2 to 16 carbon atoms, and an acylamino
group having from 2 to 16 carbon atoms. The substituent is
preferably a halogen atom, a cyano group, an alkyl group having
from 1 to 6 carbon atoms, a halogen atom-substituted alkyl group
having from 1 to 6 carbon atoms, more preferably a halogen atom,
an, alkyl group having from 1 to 4 carbon atoms, a halogen
atom-substituted alkyl group having from 1 to 4 carbon atoms, even
more preferably a halogen atom, an alkyl group having from 1 to 3
carbon atoms, or a trifluoromethyl group.
In the formula, n1 indicates an integer of from 0 to 4. n1 is
preferably an integer of from 1 to 3, more preferably 1 or 2. When
n1 is 0, then L.sup.22 in formula (DI-R) directly bonds to any of
H.sup.1 to H.sup.3. When n1 is 2 or more, then
(-L.sup.21-F.sup.1)'s may be the same or different.
In the formula, L.sup.22 represents --O--, --O--CO--, --CO--O--,
--O--CO--O--, --S--, --NH--, --SO.sub.2--, --CH.sub.2--,
--CH.dbd.CH-- or --C.ident.C--, preferably --O--, --O--CO--,
--CO--O--, --O--CO--O--, --CH.sub.2--, --CH.dbd.CH-- or more
preferably --O--, --O--CO--, --CO--O--, --O--CO--O--, or
--CH.sub.2--.
When the above group has a hydrogen atom, then the hydrogen atom
may be substituted with a substituent. Examples of the substituent
are a halogen atom, a cyano group, a nitro group, an alkyl group
having from 1 to 6 carbon atoms, a halogen atom-substituted alkyl
group having from 1 to 6 carbon atoms, an alkoxy group having from
1 to 6 carbon atoms, an acyl group having from 2 to 6 carbon atoms,
an alkylthio group having from 1 to 6 carbon atoms, an acyloxy
group having from 2 to 6 carbon atoms, an alkoxycarbonyl group
having from 2 to 6 carbon atoms, a carbamoyl group, an alkyl
group-substituted carbamoyl group having from 2 to 6 carbon atoms,
and an acylamino group having from 2 to 6 carbon atoms. Especially
preferred are a halogen atom, and an alkyl group having from 1 to 6
carbon atoms.
In the formula, L.sup.23 represents a bivalent linking group
selected from --O--, --S--, --C(.dbd.O)--, --SO.sub.2--, --NH--,
--CH.sub.2--, --CH--CH-- and --C.ident.C--, and a group formed by
linking two or more of these. The hydrogen atom in --NH--,
--CH.sub.2-- and --CH.dbd.CH-- may be substituted with any other
substituent. Examples of the substituent are a halogen atom, a
cyano group, a nitro group, an alkyl group having from 1 to 6
carbon atoms, a halogen atom-substituted alkyl group having from 1
to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms,
an acyl group having from 2 to 6 carbon atoms, an alkylthio group
having from 1 to 6 carbon atoms, an acyloxy group having from 2 to
6 carbon atoms, an alkoxycarbonyl group having from 2 to 6 carbon
atoms, a carbamoyl group, an alkyl group-substituted carbamoyl
group having from 2 to 6 carbon atoms, and an acylamino group
having from 2 to 6 carbon atoms. Especially preferred are a halogen
atom, and an alkyl group having from 1 to 6 carbon atoms. The group
substituted with the substituent improves the solubility of the
compound of formula (DI) in solvent, and therefore the composition
of the invention containing the compound can be readily prepared as
a coating liquid.
In the formula, L.sup.23 is preferably a linking group selected
from a group consisting of --O--, --C(.dbd.O)--, --CH.sub.2--,
--CH.dbd.CH-- and --C.ident.C--, and a group formed by linking two
or more of these. L.sup.23 preferably has from 1 to 20 carbon
atoms, more preferably from 2 to 14 carbon atoms. Preferably,
L.sup.23 has from 1 to 16 (--CH.sub.2--)'s, more preferably from 2
to 12 (--CH.sub.2--)'s.
In the formula, Q.sup.1 represents a polymerizing group or a
hydrogen atom. In case where the compound of formula (DI) is used
in producing optical films of which the retardation is required not
to change by heat, such as optical compensatory films, Q.sup.1 is
preferably a polymerizing group. The polymerization for the group
is preferably addition polymerization (including ring-cleavage
polymerization) or polycondensation. In other words, the
polymerizing group preferably has a functional group that enables
addition polymerization or polycondensation. Examples of the
polymerizing group are shown below.
##STR00035##
More preferably, the polymerizing group is addition-polymerizing
functional group. The polymerizing group of the type is preferably
a polymerizing ethylenic unsaturated group or a ring-cleavage
polymerizing group.
Examples of the polymerizing ethylenic unsaturated group are the
following (M-1) to (M-6):
##STR00036##
In formulae (M-3) and (M-4), R represents a hydrogen atom or an
alkyl group. R is preferably a hydrogen atom or a methyl group. Of
formulae (M-1) to (M-6), preferred are formulae (M-1) and (M-2),
and more preferred is formula (M-1).
The ring-cleavage polymerizing group is preferably a cyclic ether
group, more preferably an epoxy group or an oxetanyl group, most
preferably an epoxy group.
A liquid-crystal compound of the following formula (DII) or a
liquid-crystal compound of the following formula (DIII) is more
preferred for the discotic liquid-crystal compound for use in the
invention.
##STR00037##
In formula (DII), Y.sup.31, Y.sup.32 and Y.sup.33 each
independently represent a methine group or a nitrogen atom.
Y.sup.31, Y.sup.32 and Y.sup.33 have the same meaning as that of
Y.sup.11, Y.sup.12 and Y.sup.13 in formula (DI), and their
preferred range is also the same as therein.
In the formula, R.sup.31, R.sup.32 and R.sup.33 each independently
represent the following formula (DII-R):
##STR00038##
In formula (DII-R), A.sup.31 and A.sup.32 each independently
represent a methine group or a nitrogen atom. Preferably, at least
one of A.sup.31 and A.sup.32 is a nitrogen atom; most preferably
the two are both nitrogen atoms.
In the formula, X.sup.3 represents an oxygen atom, a sulfur atom, a
methylene group or an imino group. Preferably, X.sup.3 is an oxygen
atom.
In formula (DII-R), F.sup.2 represents a bivalent cyclic linking
group having a 6-membered cyclic structure. The 6-membered ring in
F.sup.2 may be a condensed ring. However, a monocyclic ring is
preferred to a condensed ring for it. The 6-membered ring in
F.sup.2 may be any of an aromatic ring, an aliphatic ring, or a
hetero ring. Examples of the aromatic ring are a benzene ring, a
naphthalene ring, an anthracene ring and a phenanthrene ring. An
example of the aliphatic ring is a cyclohexane ring. Examples of
the hetero ring are a pyridine ring and a pyrimidine ring.
Of the bivalent cyclic ring, the benzene ring-having cyclic group
is preferably a 1,4-phenylene group or a 1,3-phenylene group. The
naphthalene ring-having cyclic group is preferably a
naphthalene-1,4-diyl group, a naphthalene-1,5-diyl group, a
naphthalene-1,6-diyl group, a naphthalene-2,5-diyl group, a
naphthalene-2,6-diyl group, or a naphthalene-2,7-diyl group. The
cyclohexane ring-having cyclic group is preferably a
1,4-cyclohexylene group. The pyridine ring-having cyclic group is
preferably a pyridine-2,5-diyl group. The pyrimidine ring-having
cyclic group is preferably a pyrimidin-2,5-diyl group. More
preferably, the bivalent cyclic group is a 1,4-phenylene group, a
1,3-phenylene group, a naphthalene-2,6-diyl group, or a
1,4-cyclohexylene group.
In the formula, F.sup.2 may have at lease one substituent. Examples
of the substituent are a halogen atom (e.g., fluorine atom,
chlorine atom, bromine atom, iodine atom), a cyano group, a nitro
group, an alkyl group having from 1 to 16 carbon atoms, an alkenyl
group having from 2 to 16 carbon atoms, an alkynyl group having
from 2 to 16 carbon atoms, a halogen atom-substituted alkyl group
having from 1 to 16 carbon atoms, an alkoxy group having from 1 to
16 carbon atoms, an acyl group having from 2 to 16 carbon atoms, an
alkylthio group having from 1 to 16 carbon atoms, an acyloxy group
having from 2 to 16 carbon atoms, an alkoxycarbonyl group having
from 2 to 16 carbon atoms, a carbamoyl group, an alkyl
group-substituted carbamoyl group having from 2 to 16 carbon atoms,
and an acylamino group having from 2 to 16 carbon atoms. The
substituent of the bivalent cyclic group is preferably a halogen
atom, a cyano group, an alkyl group having from 1 to 6 carbon
atoms, a halogen atom-substituted alkyl group having from 1 to 6
carbon atoms, more preferably a halogen atom, an alkyl group having
from 1 to 4 carbon atoms, a halogen atom-substituted alkyl group
having from 1 to 4 carbon atoms, even more preferably a halogen
atom, an alkyl group having from 1 to 3 carbon atoms, or a
trifluoromethyl group.
In the formula, n3 indicates an integer of from 1 to 3. n3 is
preferably 1 or 2. When n3 is 2 or more, then F.sup.2's may be the
same or different.
In the formula, L.sup.31 represents --O--, --O--CO--, --CO--O--,
--O--CO--O--, --S--, --NH--, --SO.sub.2--, --CH.sub.2--, --CH--CH--
or --C.ident.C--. When the above group has a hydrogen atom, then
the hydrogen atom may be substituted with a substituent. The
preferred range of L.sup.31 may be the same as that of L.sup.22 in
formula (DI-R).
In the formula, L.sup.32 represents a bivalent linking group
selected from --O--, --S--, --C(.dbd.O)--, --SO.sub.2--, --NH--,
--CH.sub.2--, --CH.dbd.CH-- and --C.ident.C--, and a group formed
by linking two or more of these, and when the group has a hydrogen
atom, the hydrogen atom may be substituted with a substituent. The
preferred range of L.sup.32 may be the same as that of L.sup.23 in
formula (DI-R).
In the formula, Q.sup.3 represents a polymerizing group or a
hydrogen atom, and its preferred range is the same as that of
Q.sup.1 in formula (DI-R).
Compounds of formula (DIII) will be described in detail.
##STR00039##
In formula (DIII), Y.sup.41, Y.sup.42 and Y.sup.43 each
independently represent a methine group or a nitrogen atom. When
Y.sup.41, Y.sup.42 and Y.sup.43 each are a methine group, the
hydrogen atom of the methine group may be substituted with a
substituent. Preferred examples of the substituent that the methine
group may have are an alkyl group, an alkoxy group, an aryloxy
group, an acyl group, an alkoxycarbonyl group, an acyloxy group, an
acylamino group, an alkoxycarbonylamino group, an alkylthio group,
an arylthio group, a halogen atom, and a cyano group. Of those,
more preferred are an alkyl group, an alkoxy group, an
alkoxycarbonyl group, an acyloxy group, a halogen atom and a cyano
group; even more preferred are an alkyl group having from 1 to 12
carbon atoms, an alkoxy group having from 1 to 12 carbon atoms, an
alkoxycarbonyl group having from 2 to 12 carbon atoms, an acyloxy
group having from 2 to 12 carbon atoms, a halogen atom and a cyano
group.
Preferably, Y.sup.41, Y.sup.42 and Y.sup.43 are all methine groups,
more preferably non-substituted methine groups.
In the formula, R.sup.41, R.sup.42 and R.sup.43 each independently
represent the following formula (DIII-A), (DIII-B) or (DIII-C).
When retardation plates and the like having a small wavelength
dispersion are produced, the compound in which R.sup.41, R.sup.42
and R.sup.43 are represented by formula (DIII-A) or (DIII-C), more
preferably formula (DIII-A), is preferably used.
##STR00040##
In formula (DIII-A), A.sup.41, A.sup.42, A.sup.43, A.sup.44,
A.sup.45 and A.sup.46 each independently represent a methine group
or a nitrogen atom. Preferably, at least one of A.sup.41 and
A.sup.42 is a nitrogen atom; more preferably the two are both
nitrogen atoms. Preferably, at least three of A.sup.43, A.sup.44,
A.sup.45 and A.sup.46 are methine groups; more preferably, all of
them are methine groups. When A.sup.43, A.sup.44, A.sup.45 and
A.sup.46 are methine groups, the hydrogen atom of the methine group
may be substituted with a substituent. Examples of the substituent
that the methine group may have are a halogen atom (fluorine atom,
chlorine atom, bromine atom, iodine atom), a cyano group, a nitro
group, an alkyl group having from 1 to 16 carbon atoms, an alkenyl
group having from 2 to 16 carbon atoms, an alkynyl group having
from 2 to 16 carbon atoms, a halogen-substituted alkyl group having
from 1 to 16 carbon atoms, an alkoxy group having from 1 to 16
carbon atoms, an acyl group having from 2 to 16 carbon atoms, an
alkylthio group having from 1 to 16 carbon atoms, an acyloxy group
having from 2 to 16 carbon atoms, an alkoxycarbonyl group having
from 2 to 16 carbon atoms, a carbamoyl group, an alkyl
group-substituted carbamoyl group having from 2 to 16 carbon atoms,
and an acylamino group having from 2 to 16 carbon atoms. Of those,
preferred are a halogen atom, a cyano group, an alkyl group having
from 1 to 6 carbon atoms, a halogen-substituted alkyl group having
from 1 to 6 carbon atoms; more preferred are a halogen atom, an
alkyl group having from 1 to 4 carbon atoms, a halogen-substituted
alkyl group having from 1 to 4 carbon atoms; even more preferred
are a halogen atom, an alkyl group having from 1 to 3 carbon atoms,
a trifluoromethyl group.
In the formula, X.sup.41 represents an oxygen atom, a sulfur atom,
a methylene group or an imino group, but is preferably an oxygen
atom.
##STR00041##
In formula (DIII-B), A.sup.51, A.sup.52, A.sup.53, A.sup.54,
A.sup.55 and A.sup.56 each independently represent a methine group
or a nitrogen atom. Preferably, at least one of A.sup.51 and
A.sup.52 is a nitrogen atom; more preferably the two are both
nitrogen atoms. Preferably, at least three of A.sup.53, A.sup.54,
A.sup.55 and A.sup.56 are methine groups; more preferably, all of
them are methine groups. When A.sup.53, A.sup.54, A.sup.55 and
A.sup.56 are methine groups, the hydrogen atom of the methine group
may be substituted with a substituent. Examples of the substituent
that the methine group may have are a halogen atom (fluorine atom,
chlorine atom, bromine atom, iodine atom), a cyano group, a nitro
group, an alkyl group having from 1 to 16 carbon atoms, an alkenyl
group having from 2 to 16 carbon atoms, an alkynyl group having
from 2 to 16 carbon atoms, a halogen-substituted alkyl group having
from 1 to 16 carbon atoms, an alkoxy group having from 1 to 16
carbon atoms, an acyl group having from 2 to 16 carbon atoms, an
alkylthio group having from 1 to 16 carbon atoms, an acyloxy group
having from 2 to 16 carbon atoms, an alkoxycarbonyl group having
from 2 to 16 carbon atoms, a carbamoyl group, an alkyl
group-substituted carbamoyl group having from 2 to 16 carbon atoms,
and an acylamino group having from 2 to 16 carbon atoms. Of those,
preferred are a halogen atom, a cyano group, an alkyl group having
from 1 to 6 carbon atoms, a halogen-substituted alkyl group having
from 1 to 6 carbon atoms; more preferred are a halogen atom, an
alkyl group having from 1 to 4 carbon atoms, a halogen-substituted
alkyl group having from 1 to 4 carbon atoms; even more preferred
are a halogen atom, an alkyl group having from 1 to 3 carbon atoms,
a trifluoromethyl group.
In the formula, X.sup.52 represents an oxygen atom, a sulfur atom,
a methylene group or an imino group, but is preferably an oxygen
atom.
##STR00042##
In formula (DIII-C), A.sup.61, A.sup.62, A.sup.63, A.sup.64,
A.sup.65 and A.sup.66 each independently represent a methine group
or a nitrogen atom. Preferably, at least one of A.sup.61 and
A.sup.62 is a nitrogen atom; more preferably the two are both
nitrogen atoms. Preferably, at least three of A.sup.63, A.sup.64,
A.sup.65 and A.sup.66 are methine groups; more preferably, all of
them are methine groups. When A.sup.63, A.sup.64, A.sup.65 and
A.sup.66 are methine groups, the hydrogen atom of the methine group
may be substituted with a substituent. Examples of the substituent
that the methine group may have are a halogen atom (fluorine atom,
chlorine atom, bromine atom, iodine atom), a cyano group, a nitro
group, an alkyl group having from 1 to 16 carbon atoms, an alkenyl
group having from 2 to 16 carbon atoms, an alkynyl group having
from 2 to 16 carbon atoms, a halogen-substituted alkyl group having
from 1 to 16 carbon atoms, an alkoxy group having from 1 to 16
carbon atoms, an acyl group having from 2 to 16 carbon atoms, an
alkylthio group having from 1 to 16 carbon atoms, an acyloxy group
having from 2 to 16 carbon atoms, an alkoxycarbonyl group having
from 2 to 16 carbon atoms, a carbamoyl group, an alkyl
group-substituted carbamoyl group having from 2 to 16 carbon atoms,
and an acylamino group having from 2 to 16 carbon atoms. Of those,
preferred are a halogen atom, a cyano group, an alkyl group having
from 1 to 6 carbon atoms, a halogen-substituted alkyl group having
from 1 to 6 carbon atoms; more preferred are a halogen atom, an
alkyl group having from 1 to 4 carbon atoms, a halogen-substituted
alkyl group having from 1 to 4 carbon atoms; even more preferred
are a halogen atom, an alkyl group having from 1 to 3 carbon atoms,
a trifluoromethyl group.
In the formula, X.sup.63 represents an oxygen atom, a sulfur atom,
a methylene group or an imino group, but is preferably an oxygen
atom.
L.sup.41 in formula (DIII-A), L.sup.51 in formula (DIII-B) and
L.sup.61 in formula (DIII-C) each independently represent --O--,
--O--CO--, --CO--O--, --O--CO--O--, --S--, --NH--, --SO.sub.2--,
--CH.sub.2--, --CH--CH-- or --C.ident.C--; preferably --O--,
--O--CO--, --CO--O--, --O--CO--O--, --CH.sub.2--, --CH--CH-- or
--C.ident.C--; more preferably --O--, --O--CO--, --CO--O--,
--O--CO--O-- or --CH.sub.2--. When above group has a hydrogen atom,
then the hydrogen atom may be substituted with a substituent.
Preferred examples of the substituent are a halogen atom, a cyano
group, a nitro group, an alkyl group having from 1 to 6 carbon
atoms, a halogen atom-substituted alkyl group having from 1 to 6
carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, an
acyl group having from 2 to 6 carbon atoms, an alkylthio group
having from 1 to 6 carbon atoms, an acyloxy group having from 2 to
6 carbon atoms, an alkoxycarbonyl group having from 2 to 6 carbon
atoms, a carbamoyl group, an alkyl group-substituted carbamoyl
group having from 2 to 6 carbon atoms, and an acylamino group
having from 2 to 6 carbon atoms. Especially preferred are a halogen
atom, and an alkyl group having from 1 to 6 carbon atoms.
L.sup.42 in formula (DIII-A), L.sup.52 in formula (DIII-B) and
L.sup.62 in formula (DIII-C) each independently represent a
bivalent linking group selected from --O--, --S--, --C(.dbd.O)--,
--NH--, --CH.sub.2--, --CH--CH-- and --C.ident.C--, and a group
formed by linking two or more of these. The hydrogen atom in
--NH--, --CH.sub.2-- and --CH--CH-- may be substituted with a
substituent. Preferred examples of the substituent are a halogen
atom, a cyano group, a nitro group, an alkyl group having from 1 to
6 carbon atoms, a halogen atom-substituted alkyl group having from
1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon
atoms, an acyl group having from 2 to 6 carbon atoms, an alkylthio
group having from 1 to 6 carbon atoms, an acyloxy group having from
2 to 6 carbon atoms, an alkoxycarbonyl group having from 2 to 6
carbon atoms, a carbamoyl group, an alkyl group-substituted
carbamoyl group having from 2 to 6 carbon atoms, and an acylamino
group having from 2 to 6 carbon atoms. Especially preferred are a
halogen atom, and an alkyl group having from 1 to 6 carbon
atoms.
Preferably, L.sup.42, L.sup.52 and L.sup.62 each independently
represent a bivalent linking group selected from --O--,
--C(.dbd.O)--, --CH.sub.2--, --CH.dbd.CH-- and --C.ident.C--, and a
group formed by linking two or more of these. Preferably, L.sup.42,
L.sup.52 and L.sup.62 each independently have from 1 to 20 carbon
atoms, more preferably from 2 to 14 carbon atoms. Preferably,
L.sup.42, L.sup.52 and L.sup.62 each independently have from 1 to
16 (--CH.sub.2--)'s, more preferably from 2 to 12
(--CH.sub.2--)'s.
Q.sup.4 in formula (DIII-A), Q.sup.5 in formula (DIII-B) and
Q.sup.6 in formula (DIII-C) each independently represent a
polymerizing group or a hydrogen atom. Their preferred ranges are
the same as that of Q.sup.1 in formula (DI-R).
Specific examples of the compounds of formulae (DI), (DII) and
(DIII) include, but are not limited to, those shown below.
##STR00043## ##STR00044## ##STR00045## ##STR00046## ##STR00047##
##STR00048##
Examples of the compound represented by formula (DIII) include, but
are not limited to, those shown below.
##STR00049##
The compounds of the formulae (DI), (DII) and (DII) for used in the
invention may be produced according to any method.
According to the invention, as the liquid-crystal compound for used
in the invention, only one kind of the compounds of the formulae
(DI), (DII) and (DII), or two or more thereof may be used. One
feature of the compound represented by the formula (DI), (DII) or
(DII) resides in low-wavelength dependency of birefringence
developed by the alignment thereof. Therefore, if its optical
property is optimized for G light, of which wavelength is the
middle of the visible-light wavelength range, its optical
properties for R and B lights may be almost equally optimized; and,
by using such a compound, it is possible to produce easily an
optically anisotropic layer or the like having desired optical
properties for any visible light. Although it may be difficult to
align molecules of the compound represented by formula (DI), (DII)
or (DII) in a hybrid alignment state with a low mean tilt angle
(for example, equal to or lower than 40.degree.), in the presence
of the polymer mentioned above, the molecules may be aligned in a
hybrid alignment state with a low mean tilt angle furthermore
without any alignment defects (or with reduced alignment
defects).
Further, at least one kind of discotic or rod-like liquid-crystal
compounds having a different structure from the compounds of the
formulae (DI), (DII) and (DII) may be used together with it. Using
it in combination with a discotic liquid-crystal compound is
preferable, and using it in combination with a liquid-crystal
compound represented by the following formula (T) is more
preferable. By using together with at least two kinds of discotic
compounds, a tilt angle at the air surface can be reduced, and
temperature dependency of the mean tilt angle is easy to be
released.
##STR00050##
In the formula, M represents a bivalent linking group, which may be
the same or different; Q.sup.7 represents a polymerizable group or
a hydrogen atom, which may be the same or different.
In the above formula, the bivalent linking group (M) is preferably
an alkylene group, an alkenylene group, an arylene group, --CO--,
--NH--, --O-- and --S--, and a bivalent linking formed by linking
two or more thereof. The bivalent linking group (M) is more
preferably a bivalent linking group formed by linking at least two
groups selected from an alkylene group, an alkenylene group, an
arylene group, --CO--, --NH--, --O-- and --S--. The bivalent
linking group (M) is further preferably a bivalent linking group
formed by linking of at least two groups selected from an alkylene
group, an alkenylene group, an arylene group, --CO-- and --O--. The
number of the carbon atoms of the alkylene group is preferably 1 to
12, more preferably 2 to 12, and further more preferably 6 to 10.
The alkylene group, the alkenylene group and the arylene group may
have one or more substituents, for example, an alkyl group, a
halogen atom, a cyano group, an alkoxy group and an acyloxy group.
Specific examples of the bivalent linking group (M) are shown
below. In the examples, left side bonds the triphenylene dicotic
core (TD), and right side bonds the polymerizable group (Q). in the
formula, AL means an alkylene group or an alkenylene group, and AR
means an arylene group. -AL-CO--O-AL- M1 -AL-CO--O-AL-O-- M2
-AL-CO--O-AL-O-AL- M3 -AL-CO--O-AL-O--CO-- M4 --CO-AR-O-AL- M5
--CO-AR-O-AL-O-- M6 --CO-AR-O-AL-O--CO-- M7 --CO--NH-AL- M8
--NH-AL-O-- M9 --NH-AL-O--CO-- M10 --O-AL- M11 --O-AL-O-- M12
--O-AL-O--CO-- M13 --O-AL-O--CO--NH-AL- M14 --O-AL-S-AL- M15
--O--CO-AL-AR-O-AL-O--CO-- M16 --O--CO-AR-O-AL-CO-- M17
--O--CO-AR-O-AL-O--CO M18 --O--CO-AR-O-AL-O-AL-O--C M19
--O--CO-AR-O-AL-O-AL-O-AL-O--CO-- M20 --S-AL- M21 --S-AL-O-- M22
--S-AL-O--CO-- M23 --S-AL-S-AL- M24 --S-AR-AL- M25
Q.sup.7 represents a polymerizable group or a hydrogen atom, the
preferable range thereof is the same as Q.sup.1 in formula
(DI-R).
Specific examples of the compounds of formula (T) include, but are
not limited to, those shown below.
##STR00051##
The compounds of the formula (T) for used in the invention may be
produced according to any method.
The compound of the formula (T) is preferably added in the range of
1 to 20% by mass relative to the compound of the formula (DI),
(DII) or (DIII), more preferably in the range of 3 to 20% by mass,
and further more preferably in the range of 5 to 15% by mass.
Columnar phase and discotic nematic phase (N.sub.D phase) can be
exemplified as the liquid crystal phase developed by the liquid
crystalline compound used for preparing the optically anisotropic
layer. Of these liquid crystal phases, the discotic nematic phase
(N.sub.D phase) showing a desirable mono-domain property is most
preferable.
The liquid crystalline compound used for preparing the optically
anisotropic layer preferably exhibits the liquid crystal phase
within the range from 20.degree. C. to 300.degree. C., the range
being more preferably from 40.degree. C. to 280.degree. C., and
most preferably from 60.degree. C. to 250.degree. C. It is to be
understood that examples of the liquid crystal phase developed at
20.degree. C. to 300.degree. C. also include any liquid crystal
phases having the liquid-crystallinity temperature range which lies
over 20.degree. C. (for example, the range between 10.degree. C.
and 22.degree. C.), and lies over 300.degree. C. (for example, the
range between 298.degree. C. and 310.degree. C.). The same is
applicable to the ranges from 40.degree. C. to 280.degree. C. and
from 60.degree. C. to 250.degree. C.
The composition of the invention is useful for producing optically
anisotropic films. Upon producing an optically anisotropic film,
the composition of the invention is preferably prepared as a
curable composition. An additive, a curing method and the like upon
preparing the curable composition will be described with reference
to a production process of a retardation plate as an example.
[Retardation Plate]
The retardation plate of the invention comprises an optically
anisotropic layer formed of the composition of the invention. In
one embodiment, the retardation plate of the invention comprises a
support, an alignment film formed on the support, and an optically
anisotropic layer formed of the composition in which molecules are
fixed in an alignment state predetermined by the alignment
film.
The optical anisotropic layer (which may be referred to as a first
optically anisotropic layer), the alignment film and the support
(which may be referred to as a second optically anisotropic layer)
will be described in detail below.
(1) Optically Anisotropic Layer (First Optically Anisotropic
Layer)
The optically anisotropic layer is formed of a composition
containing a liquid crystal compound and a polymer comprising a
constitutional unit represented by formula (A) and a constitutional
unit derived from a monomer having a fluoroaliphatic group. The
composition is preferably a curable composition, and for example
preferably contains a polymerization initiator. The composition may
further contain various kinds of additives depending on necessity.
The composition is preferably prepared as a coating composition,
and the coating composition may be coated on a surface of an
alignment film formed on a support, followed by aligning and fixing
molecules of the liquid crystal compound, to form the optically
anisotropic layer. The support may be removed after aligning and
fixing them.
(1)-a Method of Layer Formation:
The optically-anisotropic layer may be formed by applying a coating
liquid, which is prepared by dissolving a liquid-crystal compound
and a polymer comprising the unit represented by formula (A) and
the unit derived from a monomer having a fluoroaliphatic group(s)
in a solvent capable of dissolving them, onto an alignment film
formed on a support and aligned thereon. If possible, the layer may
also be formed in a mode of vapor deposition, but is preferably
formed according to such a coating method. The coating method may
be any known method of curtain-coating, dipping, spin-coating,
printing, spraying, slot-coating, roll-coating, slide-coating,
blade-coating, gravure-coating or wire bar-coating. Next, the
coating layer is dried at 25.degree. C. to 130.degree. C. to remove
the solvent, whereupon the molecules of the liquid-crystal compound
therein are aligned and fixed by irradiation with UV rays, and the
intended optically-anisotropic layer is thus formed. UV rays are
preferably used for irradiation with light for polymerization. The
irradiation energy is preferably from 20 mJ/cm.sup.2 to 50
J/cm.sup.2, more preferably from 100 mJ/cm.sup.2 to 800
mJ/cm.sup.2. For promoting the optical polymerization, the light
irradiation may be attained under heat. Thus formed, the thickness
of the optically-anisotropic layer may vary, depending on the
optimum retardation value in accordance with the use of the layer
for optical compensation or the like, but is preferably from 0.1 to
10 .mu.m, more preferably from 0.5 to 5 .mu.m.
Preferably, molecules of the liquid-crystal compound are
substantially uniformly aligned in the optically-anisotropic layer;
more preferably, the molecules are fixed while substantially
uniformly aligned therein; most preferably, the liquid-crystal
compound is fixed through polymerization.
The ratio of the compound of formula (DI) or a polymer made of the
compound of formula (DI) in the optically-anisotropic layer is
preferably from 10 to 100% by mass, more preferably from 30 to 99%
by mass, and even more preferably from 50 to 99% by mass.
(1)-b Other Materials for Use in Preparation of
Optically-Anisotropic Layer:
Preferably, the liquid-crystal compound is fixed while kept aligned
in the optically-anisotropic layer, in which it is desirable that
the fixation of the liquid-crystal compound is attained through
polymerization of the polymerizing group introduced into the
compound. For this, the coating liquid for the layer preferably
contains a polymerization initiator. Polymerization includes
thermal polymerization with a thermal polymerization initiator,
photopolymerization with a photopolymerization initiator, and EB
curing with electronic beams. Of those, preferred are
photopolymerization (photocuring) and EB curing. Preferred examples
of the polymerization initiator that generates a radical by the
action of light given thereto are .alpha.-carbonyl compounds (as in
U.S. Pat. Nos. 2,367,661, 2,367,670), acyloin ethers (as in U.S.
Pat. No. 2,448,828,) .alpha.-hydrocarbon-substituted aromatic
acyloin compounds (as in U.S. Pat. No. 2,722,512), polycyclic
quinone compounds (as in U.S. Pat. Nos. 3,046,127, 2,951,758),
combination of triarylimidazole dimer and p-aminophenyl ketone (as
in U.S. Pat. No. 3,549,367), acridine and phenazine compounds (as
in JP-A 60-105667, U.S. Pat. No. 4,239,850) and oxadiazole
compounds (as in U.S. Pat. No. 4,212,970), acetophenone compounds,
benzoin ether compounds, benzyl compounds, benzophenone compounds,
thioxanthone compounds. Examples of the acetophenone compound
include, for example, 2,2-diethoxyacetophenone,
2-hydroxymethyl-1-phenylpropan-1-one,
4'-isopropyl-2-hydroxy-2-methyl-propiophenone,
2-hydroxy-2-methyl-propiophenone, p-dimethylaminoacetone,
p-tert-butyldichloroacetophenone, p-tert-butyltrichloroacetopheone,
p-azidobenzalacetophenone. Examples of the benzyl compound include,
for example, benzyl, benzyl dimethyl ketal, benzyl
.beta.-methoxyethyl acetal, 1-hydroxycyclohexyl phenyl ketone. The
benzoin ether compounds include, for example, benzoin, benzoin
methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin
isopropyl ether, benzoin n-butyl ether, and benzoin isobutyl ether.
Examples of the benzophenone compound include benzophenone, methyl
o-benzoylbenzoate, Michler's ketone,
4,4'-bisdiethylaminobenzophenone, 4,4'-dichlorobenzophenone.
Examples of the thioxanthone compound include thioxanthone,
2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone,
4-isopropylthioxanthone, 2-chlorothioxanthone, and
2,4-diethylthioxanthone. Of those aromatic ketones serving as a
light-sensitive radical polymerization initiator, more preferred
are acetophenone compounds and benzyl compounds in point of their
curing capability, storage stability and odorlessness. One or more
such aromatic ketones may be used herein as a light-sensitive
radical polymerization initiator, either singly or as combined
depending on the desired performance of the initiator.
For the purpose of increasing the sensitivity thereof, a sensitizer
may be added to the polymerization initiator. Examples of the
sensitizer are n-butylamine, triethylamine, tri-n-butyl phosphine,
and thioxanthone.
Plural types of the photopolymerization initiators may be combined
and used herein, and the amount thereof is preferably from 0.01 to
20% by mass of the solid content of the coating liquid, more
preferably from 0.5 to 5% by mass. For light irradiation for
polymerization of the liquid-crystal compound, preferably used are
UV rays.
The solvent to be used in preparing the coating liquid for the
optically-anisotropic layer is preferably an organic solvent.
Examples of the organic solvent are amides (e.g.,
N,N-dimethylformamide), sulfoxides (e.g., dimethylsulfoxide),
heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g.,
toluene, hexane), alkyl halides (e.g., chloroform,
dichloromethane), esters (e.g., methyl acetate, butyl acetate),
ketones (e.g., acetone, 2-butanone, methyl isobutyl ketone,
cyclohexanone), ethers (e.g., tetrahydrofuran,
1,2-dimethoxyethane). Of those, preferred are alkyl halides and
ketones. Two or more different types of organic solvents may be
combined for use herein.
The solid concentration of the liquid-crystal compound and other
additives in the composition of the invention is preferably from
0.1% by mass to 60% by mass, more preferably from 0.5% by mass to
50% by mass, even more preferably 2% by mass to 40% by mass.
(1)-c Alignment State:
When used in a OCB (Optically Compensatory Bend) liquid-crystal
mode as a retardation plate, the optically-anisotropic layer formed
with the composition of the invention is preferably such that its
discotic nematic phase is in a hybrid alignment state. The term
"Hybrid alignment" as referred to herein means that the a tilt
angle of a liquid-crystal molecule (regarding discotic liquid
crystal molecule, a tilt angle of a discotic plane of the molecule
relative to the layer plane) in the layer continuously varies in
the direction of the thickness of the film.
When applied onto a support (more preferably onto an alignment
film), a liquid-crystal compound may express its liquid-crystal
phase, for example, after heated thereon. Accordingly, in the
interface adjacent to the support, the liquid-crystal compound may
be aligned at a tilt angle to the support surface or to the coating
film interface (when an alignment film is provided, this is the
alignment film interface) (for example, when a discotic
liquid-crystal compound is used, the tilt angle is an angle formed
by the direction of the support surface and the direction of the
disc face of the liquid-crystal compound), and in interface
adjacent to air, the compound may be aligned at a tilt angle to the
air interface.
In the invention, the mean tilt angle of the optically-anisotropic
layer (for example, the angle formed by the direction of the
support surface and the direction of the disc face of the discotic
liquid-crystal compound) is preferably from 10 to 40.degree., more
preferably from 15 to 35.degree..
(2) Alignment Film
An alignment film may be used upon producing the retardation plate
of the invention. The alignment film may be formed, for example,
through rubbing treatment of a compound (preferably polymer),
oblique vapor deposition of an inorganic compound, formation of a
microgrooved layer, or accumulation of an organic compound (e.g.,
.omega.-tricosanoic acid, dioctadecylmethylammonium chloride,
methyl stearate) according to a Langmuir-Blodgett's method (LB
film). Further, there are known other alignment films that may have
an alignment function through impartation of an electric field or
magnetic field thereto or through light irradiation thereto.
In principle, the polymer to be used for the alignment film has a
molecular structure that has the function of aligning
liquid-crystal molecules. Preferably, the polymer for use in the
invention has crosslinking functional group (e.g., double
bond)-having side chains bonded to the backbone chain thereof or
has a crosslinking functional group having the function of aligning
liquid-crystal molecules introduced into the side chains thereof,
in addition to having the function of aligning liquid-crystal
molecules. The polymer to be used for the alignment film may be a
polymer that is crosslinkable by itself or a polymer that is
crosslinkable with a crosslinking agent, or may also be a
combination of the two.
Examples of the polymer are methacrylate polymers, styrene
polymers, polyolefins, polyvinyl alcohols and modified polyvinyl
alcohols, poly(N-methylolacrylamides), polyesters, polyimides,
vinyl acetate polymers, carboxymethyl cellulose and polycarbonates,
as in JPA No. hei 8-338913, [0022]. A silane coupling agent is also
usable as the polymer. Preferably, the polymer is a water-soluble
polymer (e.g., poly(N-methylolacrylamide), carboxymethyl cellulose,
gelatin, polyvinyl alcohol, modified polyvinyl alcohol), more
preferably gelatin, polyvinyl alcohol or modified polyvinyl
alcohol, even more preferably polyvinyl alcohol or modified
polyvinyl alcohol. Especially preferably, two different types of
polyvinyl alcohols or modified polyvinyl alcohols having a
different degree of polymerization are combined for use as the
polymer.
Preferably, the degree of saponification of polyvinyl alcohol for
use herein is from 70 to 100%, more preferably from 80 to 100%.
Also preferably, the degree of polymerization of polyvinyl alcohol
is from 100 to 5000.
The side chains having the function capable of aligning
liquid-crystal molecules generally have a hydrophobic group as the
functional group. Concretely, the type of the functional group may
be determined depending on the type of the liquid-crystal molecules
to be aligned and on the necessary alignment state of the
molecules.
For example, the modified group of modified polyvinyl alcohol may
be introduced into the polymer through copolymerization
modification, chain transfer modification or block polymerization
modification. Examples of the modified group include a hydrophilic
group (e.g., carboxylic acid group, sulfonic acid group, phosphonic
acid group, amino group, ammonium group, amido group, thiol group),
a hydrocarbon group having from 10 to 100 carbon atoms, a fluorine
atom-substituted hydrocarbon group, a thioether group, a
polymerizing group (e.g., unsaturated polymerizing group, epoxy
group, aziridinyl group), and an alkoxysilyl group (e.g., trialkoxy
group, dialkoxy group, monoalkoxy group). Specific examples of such
modified polyvinyl alcohol compounds are described, for example, in
JPA No. 2000-155216, [0022] to [0145], and in JPA No. 2002-62426,
[0018] to [0022].
When crosslinking functional group-having side chains are bonded to
the backbone chain of an alignment film polymer, or when a
crosslinking functional group is introduced into the side chains of
a polymer having the function of aligning liquid-crystal molecules,
then the polymer of the alignment film may be copolymerized with
the polyfunctional monomer in an optically-anisotropic layer. As a
result, not only between the polyfunctional monomers but also
between the alignment film polymers, and even between the
polyfunctional monomer and the alignment film polymer, they may be
firmly bonded to each other in a mode of covalent bonding to each
other. Accordingly, introducing such a crosslinking functional
group into an alignment film polymer significantly improves the
mechanical strength of the resulting retardation plate.
Preferably, the crosslinking functional group of the alignment film
polymer contains a polymerizing group, like the polyfunctional
monomer. Concretely, for example, those described in JPA No.
2000-155216, [0080] to [0100] are referred to herein.
Apart from the above-mentioned crosslinking functional group, the
alignment film polymer may also be crosslinked with a crosslinking
agent.
The crosslinking agent includes, for example, aldehydes, N-methylol
compounds, dioxane derivatives, compounds capable of being active
through activation of the carboxyl group thereof, active vinyl
compounds, active halide compound, isoxazoles and dialdehyde
starches. Two or more different types of crosslinking agents may be
combined for use herein. Concretely, for example, the compounds
described in JPA No. 2002-62426, [0023] to [0024] are employable
herein. Preferred are aldehydes of high reactivity, and more
preferred is glutaraldehyde.
Preferably, the amount of the crosslinking agent to be added to
polymer is from 0.1 to 20% by mass of the polymer, more preferably
from 0.5 to 15% by mass. Also preferably, the amount of the
unreacted crosslinking agent that may remain in the alignment film
is at most 1.0% by mass, more preferably at most 0.5% by mass. When
the crosslinking agent in the alignment film is controlled to that
effect, then the film ensures good durability with no reticulation
even though it is used in liquid-crystal display devices for a long
period of time and even though it is left in a high-temperature
high-humidity atmosphere for a long period of time.
Basically, the alignment film may be formed by applying the
alignment film-forming material of the above-mentioned polymer to a
crosslinking agent-containing transparent support, then heating and
drying it for crosslinking it and then optionally rubbing the
thus-formed film. The crosslinking reaction may be effected in any
stage after the film-forming material has been applied onto the
transparent support, as so mentioned hereinabove. When a
water-soluble polymer such as polyvinyl alcohol is used as the
alignment film-forming material, then it is desirable that the
solvent for the coating liquid is a mixed solvent of a defoaming
organic solvent (e.g., methanol) and water. The ratio by mass of
water/methanol is preferably (more than 0 to 99)/(100 to less than
1), more preferably (more than 0 to 91)/(less than 100 to 9). The
mixed solvent of the type is effective for preventing the formation
of bubbles in the coating liquid and, as a result, the surface
defects of the alignment film and even the optically-anisotropic
layer are significantly reduced.
For forming the alignment film, preferably employed is a
spin-coating method, a dip-coating method, a curtain-coating
method, an extrusion-coating method, a rod-coating method or a
roll-coating method. Especially preferred is a rod-coating method.
Also preferably, the thickness of the film is from 0.1 to 10 .mu.m,
after dried. The drying under heat may be effected, for example, at
20 to 110.degree. C. For sufficient crosslinking, the heating
temperature is preferably from 60 to 100.degree. C., more
preferably from 80 to 100.degree. C. The drying time may be from 1
minute to 36 hours, but preferably from 1 to 30 minutes. The pH of
the coating liquid is preferably so defined that it is the best for
the crosslinking agent used. For example, when glutaraldehyde is
used, the pH of the coating liquid is preferably from 4.5 to 5.5,
more preferably pH 5.
The alignment film is provided on a support or on an undercoat
layer. The alignment film may be formed by crosslinking the polymer
layer as above, and then rubbing the surface of the layer.
A rubbing method having been widely employed as an orientation
method of a liquid crystal of a liquid crystal display device may
be used. Specifically, the surface of the film is rubbed in one
direction with paper, gauze, felt, rubber or nylon or polyester
fibers to attain orientation. In general, the film is rubbed
several times with a cloth having fibers having uniform length and
thickness implanted uniformly. A rubbing roll having a circularity,
a cylindricity and a deflection (eccentricity) that are all 30
.mu.m or less is preferably used. The wrap angle of the film on the
rubbing roll is preferably from 0.1 to 90.degree.. However, for
example, the film may be wrapped at an angle of 360.degree. or more
to attain the rubbing treatment stably, as shown in JPA No. hei
8-160430. In the case where a film in a long strip form is rubbed,
the film is preferably conveyed with a conveying device at a speed
of from 1 to 100 m/min under a constant tension. The rubbing roll
is preferably rotatable in a horizontal direction with respect to
the film conveying direction for setting an arbitrary rubbing
angle. The rubbing angle is preferably selected from a range of
from 0 to 60.degree., and in the case where the film is used in a
liquid crystal display device, the rubbing angle is preferably from
40 to 50.degree., and more preferably 45.degree..
After the liquid-crystal compound is aligned on the alignment film,
if desired, the alignment film polymer and the polyfunctional
monomer in the optically-anisotropic layer may be reacted, or the
alignment film polymer may be crosslinked with a crosslinking
agent. Preferably, the thickness of the alignment film is from 0.1
to 10 .mu.m. A coating liquid prepared by dissolving the
above-mentioned alignment film polymer in a solvent is applied onto
the surface of a support, and then the solvent in the coating
liquid is removed and dried at 25.degree. C. to 140.degree. C. to
thereby form the intended alignment film. If possible, the film may
also be formed in a mode of vapor deposition, but is preferably
formed according to a coating process. The thickness of the
alignment film thus formed is preferably from 0.01 to 5 .mu.m, more
preferably from 0.05 to 2 .mu.m.
The solvent for use in preparing the alignment film-forming coating
liquid includes, for example, water, alcohols (e.g., methanol,
ethanol, isopropanol), amides (e.g., N,N-dimethylformamide),
acetonitrile, acetone, methyl ethyl ketone, methyl isobutyl ketone,
ethyl acetate; preferably water, alcohols and their mixed solvents.
The concentration of the alignment film polymer in the coating
liquid is preferably from 0.1% by mass to 40% by mass, more
preferably from 0.5% by mass to 20% by mass, even more preferably
from 2% by mass to 10% by mass. The viscosity of the coating liquid
is preferably from 0.1 cp to 100 cp, more preferably from 0.5 cp to
50 cp.
The coating liquid may contain any other additives in addition to
the above-mentioned alignment film polymer therein. For example,
when the alignment film polymer is hardly soluble in a
water-soluble solvent, then a basic compound (e.g., sodium
hydroxide, lithium hydroxide, triethylamine) or an acid compound
(e.g., hydrochloric acid, acetic acid, succinic acid) may be added
thereto to promote its dissolution in the solvent.
The alignment film formed according to the above method is
preferably rubbed on its surface thereby having a property of
aligning liquid-crystal molecules. The rubbing treatment may be
attained by rubbing the surface of the polymer-coated surface a few
times with paper or cloth in one direction (generally in the
machine direction). Apart from such rubbing treatment, the
alignment film may also be processed for impartation of an electric
field of a magnetic field thereto, thereby having a property of
aligning liquid-crystal molecules. For making the alignment film
have the property of aligning liquid-crystal molecules, preferred
is the method of rubbing the alignment film in which the
thus-rubbed polymer may have the intended property.
(3) Support (Second Optically Anisotropic Layer)
The optical compensation film of the invention preferably comprises
a second optically anisotropic layer exhibiting optical anisotropy
in addition to the first optically anisotropic layer.
The second optically anisotropic layer functions as a support for
the first optically anisotropic layer and has a function of
broadening the controllable range of the optical characteristics of
the optical compensation film to improve the display
characteristics of the liquid display device. In other words, the
second optical anisotropic layer of the invention can be understood
as the aforementioned support that has optical anisotropy.
The second optically anisotropic layer of the invention contains at
least one sheet of a polymer film. The expression "the layer
contains a polymer film" herein means not only that the layer is
constituted only by the polymer, but also that the layer may
further contain other substances in a range that does not impair
the advantages of the invention. That is, the film mainly contains
the polymer.
Specifically, the second optically anisotropic layer preferably has
an Rth value of from 100 to 300 nm measured with light having a
wavelength of 550 nm, and more preferably from 150 to 200 nm. The
second optically anisotropic layer preferably has an Re value of
from 30 to 60 nm, and more preferably from 35 to 50 nm. In the case
where the Rth and Re values thereof are in the ranges,
respectively, the display characteristics, such as the viewing
angle characteristics, of the liquid display device can be
advantageously improved.
The second optically anisotropic layer may be constituted by only
one sheet of the polymer film or by two or more sheets of the
polymer films. The Re and Rth values in the aforementioned ranges
can be attained with only one sheet of the polymer film, and
therefore, the second optically anisotropic layer is preferably
constituted by one sheet of the polymer film.
The polymer to be employed in production of the second optically
anisotropic layer is preferably selected from cellulose based
polymers, more preferably from cellulose esters, and even more
preferably from cellulose acylates. Using cellulose acylate is
advantageous in terms of controlling optical properties.
Preferred are lower fatty acid esters of cellulose. The term "lower
fatty acid" herein means fatty acid having 6 or smaller number of
carbon atoms. The number of carbon atoms is preferably 2 (cellulose
acetate), 3 (cellulose propionate) or 4 (cellulose butyrate).
Cellulose acetate is particularly preferable. Also mixed aliphatic
acid ester such as cellulose acetate propionate and cellulose
acetate butyrate may be used.
Viscosity-average degree of polymerization (DP) of cellulose
acetate (also referred to as acetyl cellulose) is preferably 250 or
larger, and more preferably 290 or larger. The cellulose ester
(cellulose acetate) used in the present invention may preferably
have a narrow range of distribution in terms of Mw/Mn (Mw
represents mass-average molecular weight, and Mn represents
number-average molecular weight) measured by gel permeation
chromatography. More specifically, Mw/Mn preferably falls in the
range from 1.00 to 1.70, more preferably from 1.30 to 1.65, and
still more preferably from 1.40 to 1.60.
The degree of acetylation of cellulose acetate is preferably 55.0
to 62.5%, and more preferably 59.0 to 61.5%. The degree of
acetylation herein means an amount of attached acetic acid moiety
per unit mass of cellulose. The degree of acetylation may be
decided according to measurement and calculation specified by ASTM
D-817-91 (method of testing cellulose acetate and so forth).
In general, hydroxyl groups at the 2-, 3- and 6-positions are not
equally shared for 1/3 each of the total degree of distribution,
wherein hydroxyl group at the 6-position tends to be less
substituted. In the present invention, it is more preferable that
the degree of substitution of hydroxyl groups at the 6-position is
larger than that at the 2- and 3-positions. The degree of
substitution by the acetyl groups at the 6-position is preferably
from 30% to 40%, more preferably from 31% to 40%, and even more
preferably from 32 to 40% with respect to the total degree of
substitution. And the degree of substitution by the acetyl groups
at the 6-position of cellulose acetate is preferably 0.88 or
more.
Cellulose acylates and producing methods thereof which can be
employed in the invention are described in detail in Hatsumei
Kyokai Disclosure Bulletin 2001-1745, pp. 9, published by Japan
Institute of Invention and Innovation, Mar. 15, 2001.
One exemplary method for controlling retardation of a cellulose
acetate film is applying an external force to the film, in
particular, stretching the film. A retardation enhancer may be
added to a cellulose acylate film for controlling retardation
thereof. The retardation enhancer is preferably selected from
aromatic compounds having two or more aromatic rings therein. The
amount of the aromatic compound in the film is preferably from 0.01
to 20% by mass with respect to the amount of the polymer. Plural
types of aromatic compounds may be used. Examples of the aromatic
ring in the aromatic compound include not only aromatic hydrocarbon
rings but also aromatic hetero rings.
The second optically anisotropic film is preferably a cellulose
acetate film. The cellulose acetate film preferably has a
hygroscopic expansion coefficient of 30.times.10.sup.-5/% RH or
less, more preferably 15.times.10.sup.-5% RH or less, and further
preferably 10.times.10.sup.-5/% RH or less.
The hygroscopic expansion coefficient is preferably as small as
possible, but is generally a value of 1.0.times.10.sup.-5/% RH or
more. The hygroscopic expansion coefficient referred herein means
the variation of the length of the specimen where the relative
humidity is changed under a constant temperature. By controlling
the hygroscopic expansion coefficient, increase in transmittance in
a frame form (light leakage due to distortion) of the optical
compensation film can be prevented from occurring with the optical
compensation function thereof maintained.
The hygroscopic expansion coefficient can be measured in the
following manner. A specimen having a width of 5 mm and a length of
20 mm cut out from the polymer film is fixed at one end thereof and
suspended in an atmosphere of 25.degree. C. and 20% RH (R.sub.0). A
weight of 0.5 g is attached to the other end of the specimen, which
is then allowed to stand for 10 minutes, and the length (L.sub.0)
of the specimen is measured. The humidity is increased to 80% RH
(R.sub.1) with a temperature of 25.degree. C. maintained, and then
the length (L.sub.1) of the specimen is measured. The hygroscopic
expansion coefficient is calculated by the following expression.
The measurement is carried out for 10 specimens for one kind of the
polymer film, and the average value is designated as the measured
value. (hygroscopic expansion coefficient (%
RH))=((L.sub.1-L.sub.0/L.sub.0)/(R.sub.1-R.sub.0)
For decreasing the dimensional change due to moisture absorption of
a cellulose acetate film, a hydrophobic compound is preferably
added to the cellulose acetate film. The hydrophobic compound may
be in the form of fine particles. The hydrophobic compound is
preferably selected from a plasticizer and a deterioration
preventing agent. The hydrophobic compound preferably has a
hydrocarbon group (an aliphatic group or an aromatic group) as the
hydrophobic group.
The addition amount of the hydrophobic group is preferably from
0.01 to 10% by mass based on the polymer solution (dope)
prepared.
For decreasing the dimensional change due to moisture absorption of
the polymer film, it is also possible to decrease the free volume
in the polymer film. For example, the free volume is decreased by
decreasing the remaining solvent amount in the solvent cast method
described later. The polymer film is preferably dried under
conditions that provide a remaining solvent amount of from 0.01 to
1.00% by mass based on the polymer film.
Examples of the additives for the polymer film include an
ultraviolet ray preventing agent, a releasing agent, an antistatic
agent, a deterioration preventing agent (such as an antioxidant, a
peroxide decomposing agent, a radical inhibitor, a metal
inactivating agent, an oxygen scavenger and an amine) and an
infrared ray absorbent.
Regarding multi-layered polymer films, the type(s) and amount(s) of
the additive(s) in each layer may be same with or different from
those in other layer.
Additives which can be employed in the invention are described in
detail in Hatsumei Kyokai Disclosure Bulletin 2001-1745, pp. 16-22,
published by Japan Institute of Invention and Innovation, Mar. 15,
2001. The mount of an additive in the film is generally from 0.001
to 25% by mass.
The cellulose acylate film is preferably produced according to a
solvent-casting process. According to the solvent-casting process,
a solution (dope) which is prepared by dissolving polymer material
in an organic solvent is used.
The organic solvent preferably contains ether having 3 to 12 carbon
atoms, ketone having 3 to 12 carbon atoms, ester having 3 to 12
carbon atoms, or halogenated hydrocarbon having 1 to 6 carbon
atoms. The ether, ketone and ester may have cyclic structures. Any
compounds having two or more functional groups of these ether,
ketone and ester (that is, --O--, --CO-- and --COO--) may be
adoptable as the organic solvent.
The organic solvent may have also other functional groups such as
alcoholic hydroxyl group. As for any organic solvents, having two
or more species of functional group, it is good enough that the
number of carbon atoms falls in any specified range of compounds
having any of these functional groups.
Examples of the ether having 3 to 12 carbon atoms include
diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane,
1,3-dioxolane, tetrahydrofuran, anisole and phenetol. Examples of
the ketone having 3 to 12 carbon atoms include acetone, methyl
ethyl ketone, diethyl ketone, diisobutylketone, cyclohexanone and
methyl cyclohexanone. Examples of the ester having 3 to 12 carbon
atoms include ethyl formate, propyl formate, pentyl formate, methyl
acetate, ethyl acetate and pentyl acetate.
Examples of the organic solvent having two species of more
functional group include 2-ethoxyethyl acetate, 2-methoxy ethanol
and 2-butoxy ethanol. The number of carbon atoms of the halogenated
hydrocarbon is preferably 1 or 2, and most preferably 1. Halogen in
the halogenated hydrocarbon is preferably chlorine. For the case
where the hydrogen atoms of the halogenated hydrocarbon are
substituted by halogen, a ratio of substitution by halogen
preferably falls in the range from 25 to 75 mol %, more preferably
from 30 to 70 mol %, still more preferably from 35 to 65 mol %, and
most preferably from 40 to 60 mol %. Methylene chloride is a
representative halogenated hydrocarbon. Two or more species of
organic solvents may be used in a mixed manner.
The cellulose acetate solution may be prepared by any general
method. The general method herein means treatment at a temperature
of 0.degree. C. or above (normal temperature or higher
temperatures). Preparation of the solution may be carried out by
adopting methods and apparatuses for preparing dope in general
solvent cast process. In the general method, halogenated
hydrocarbon (in particular methylene chloride) may preferably used
as the organic solvent. Amount of cellulose acetate is preferably
adjusted as being contained to as much as 10 to 40% by mass, and
more preferably 10 to 30% by mass, in the resultant cellulose
acetate solution. The organic solvent (main solvent) may be added
with arbitrary additives described later. The solution may be
prepared by stirring cellulose acetate and an organic solvent at
normal temperature (0 to 40.degree. C.). A high concentration
solution may be stirred under pressure or heating conditions. More
specifically, cellulose acetate and an organic solvent are placed
in a pressure vessel, the vessel is tightly closed, and the mixture
is stirred under pressure while being heated to a range of
temperature not lower than the boiling point under normal pressure
of the solvent, so as to keep the solvent unboiled. The heating
temperature is normally 40.degree. C. or above, preferably 60 to
200.degree. C., and more preferably 80 to 110.degree. C.
The individual components may be placed in the vessel as being
preliminarily mixed. Alternatively, they may be placed into the
vessel sequentially. The vessel is preferably composed so as to
allow stirring. The vessel may be pressurized as being injected by
an inert gas such as nitrogen gas. Alternatively, elevation of
vapor pressure under heating may be available. Still alternatively,
the vessel is tightly closed, and then added with the individual
components under pressure. Heating is preferably given from the
external of the vessel. For example, a jacket-type heating
apparatus may be adoptable. Alternatively, a plate heater may be
placed outside the vessel, a piping may be attached thereto, and a
liquid medium may be allowed to circulate therethrough so as to
heat the entire vessel. Stirring is preferably effected by using a
stirring propeller provided inside the vessel. The stirring
propeller is preferably as long as reaching close to the vessel
wall. The stirring propeller is preferably provided with a scraper
blade for refreshing liquid film formed on the vessel wall. The
vessel may be provided also with measurement instruments such as a
pressure gauge, thermometer and so forth. The individual components
may be dissolved into the solvent within the vessel. The prepared
dope may be taken out from the vessel after being cooled, or may be
cooled using a heat exchanger or the like after being taken
out.
The solution may be prepared also by the cooled solubilization
method. By the cooled solubilization method, cellulose acetate may
be solubilized also into an organic solvent into which cellulose
acetate cannot readily be dissolved by general methods of
dissolution.
The cooled solubilization method is preferable also for solvents
allowing cellulose acetate to dissolve therein by the general
methods, because a homogeneous solution may rapidly be
obtained.
In the cooled solubilization method, first, cellulose acetate is
gradually added to an organic solvent under stirring at room
temperature. The amount of cellulose acetate is preferably adjusted
to 10 to 40% by mass of the mixture. The amount of cellulose
acetate is more preferably adjusted to 10 to 30% by mass.
Alternatively, the mixture may further be added with arbitrary
additives described later.
Next, the mixture is cooled to -100 to -10.degree. C. (preferably
-80 to -10.degree. C., more preferably -50 to -20.degree. C., and
most preferably -50 to -30.degree. C.). The cooling may be carried
out typically in a diethylene glycol solution (-30 to -20.degree.
C.) cooled on a dry ice-methanol bath (-75.degree. C.). Under such
cooling, a mixture of cellulose acetate and the organic solvent
solidifies. Rate of cooling is preferably 4.degree. C./min or
faster, more preferably 8.degree. C./min or faster, and most
preferably 12.degree. C./min or faster. Faster rate of cooling is
more preferable, wherein theoretical upper limit may be
10000.degree. C./sec, technical upper limit may be 1000.degree.
C./sec, and practical upper limit may be 100.degree. C./sec.
The rate of cooling herein is a value obtained by dividing
difference between the temperature at the start of cooling and the
temperature finally reached by the cooling, by length of time
ranging from the start of cooling up to when the final temperature
of cooling is reached.
A homogeneous solution may be obtained in this way. Operations of
cooling and heating may be repeated if the dissolution is
insufficient. Whether the dissolution is sufficient or not may be
judged by visual observation of appearance of the solution.
In the cooled solubilization method, a sealable vessel is
preferably used in order to avoid contamination by moisture due to
dewing in the process of cooling.
In the process of cooling and heating, pressurizing in the process
of cooling and reducing pressure in the process of heating may
shorten the time for solubilization. A pressure-proof vessel is
preferably used so as to allow pressurizing and reduction in
pressure. For example, a 20%-by-mass solution of cellulose acetate
having a degree of acetylation of 60.9% and a viscosity-average
degree of polymerization of 299, dissolved in methyl acetate by the
cooled solubilization method was found to have a quasi-phase
transition point between sol state and gel state at around
33.degree. C., when measured by differential scanning calorimetry
(DSC), showing a uniform gel state at and below the temperature. It
is therefore necessary to keep this solution at or above the
quasi-phase transition point, and preferably at a temperature
approximately 10.degree. C. higher than a gel phase transition
temperature.
It is, however, to be noted that the quasi-phase transition
temperature may vary depending on the degree of acetylation and
viscosity-average degree of polymerization of cellulose acetate,
concentration of the solution, and organic solvent to be
adopted.
As described previously, the cellulose acetate film is preferably
produced from the prepared cellulose acetate solution (dope)
according to the solvent cast method.
For the purpose of producing the cellulose acetate film used as the
support of the optical compensation sheet, the dope is preferably
added with the above-described retardation enhancer. The dope is
cast on a drum or band, from which the solvent is vaporized off to
thereby form the film. The dope before being cast is preferably
adjusted in the concentration thereof so that the solid content
falls in the range from 18 to 35%. Surfaces of the drum and the
band are preferably finished to a mirror-like state. Methods of
casting and drying in the solvent cast method are described in
patent specifications of U.S. Pat. Nos. 2,336,310, 2,367,603,
2,492,078, 2,492,977, 2,492,978, 2,607,704, 2,739,069 and
2,739,070, British Patent Nos. 640731 and 736892, Examined Japanese
Patent Publication Nos. S45-4554 and S49-5614, Japanese Laid-Open
Patent Publication Nos. S60-176834, S60-203430 and S62-115035.
The dope is preferably cast on the drum or the band having a
surface temperature of 10.degree. C. or lower. The cast solution is
preferably dried under air blow for 2 seconds or longer after the
casting.
Alternatively, the obtained film may be separated from the drum or
the band, and the residual solvent may be vaporized by drying under
hot air blow, while sequentially varying the temperature thereof
from 100 to 160.degree. C.
This method is described in Examined Japanese Patent Publication
No. H5-17844, by which the length of time from casting to
separation may desirably be shortened. In order to carry out this
method, the dope may necessarily be gellated at the surface
temperature of the drum and the band in the process of casting.
The casting may be carried out so as to form two layers using
thus-prepared cellulose acetate solution (dope), and make them into
a film. In this case, the cellulose acetate film may preferably be
produced by the solvent cast process. The dope is cast onto the
drum or the band, from which the solvent is vaporized off to
thereby form the film. The dope before being cast is preferably
adjusted in the concentration thereof so that the solid content
falls in the range from 10 to 40%. Surfaces of the drum and the
band are preferably finished to a mirror-like state.
For the case where two or more layers of cellulose acetate solution
are cast, a plurality of cellulose acetate solutions may be cast,
wherein the film may be produced by stacking the solutions
containing cellulose acetate, cast respectively from a plurality of
casting ports provided at intervals in the direction of feeding of
the support. The methods typically described in Japanese Laid-Open
Patent Publication Nos. S61-158414, H1-122419, and H11-198285 may
be applicable.
Alternatively, the film may be produced also by casting the
cellulose acetate solutions from two casting ports. The methods
typically described in Examined Japanese Patent Publication No.
60-27562, Japanese Laid-Open Patent Publication Nos. S61-94724,
S61-947245, S61-104813, 561-158413, and H6-134933 may be
applicable.
Alternatively, a method of forming a cellulose acetate film by
casting, described in Japanese Laid-Open Patent Publication No.
S56-162617, by which flow of a high-viscosity cellulose acetate
solution is wrapped by a low-viscosity cellulose acetate solution,
and the high- and low-viscosity cellulose acetate solutions are
extruded at the same time.
Alternatively, the film may be produced also by using two casting
ports, wherein a film formed on a support using a first casting
port is separated off, and a second casting is carried out on the
surface of the film, which had been brought into contact with the
surface of support. For example, a method described in Examined
Japanese Patent Publication No. S44-20235 may be exemplified.
The cellulose acetate solutions to be cast may be same or
different. In order to give functions to a plurality of cellulose
acetate layers, the cellulose acetate solutions correspondent to
the functions may be cast from the individual casting ports.
The cellulose acetate solutions may also be cast together with
other functional layers (for example, adhesive layer, dye layer,
antistatic layer, anti-halation layer, ultraviolet absorbing layer,
and polarizer layer).
In the conventional single-layer liquid process, it has been
necessary to extrude a high-concentration, high-viscosity cellulose
acetate solution in order to achieve a necessary thickness of the
film. However, this process has often suffered from a problem of
causing granulation failure and flatness failure, due to poor
stability of the cellulose acetate solution such as producing solid
matters.
As a solving means for this problem, a plurality of cellulose
acetate solutions may be cast from the casting ports, and thereby
not only high-viscosity solutions may be extruded onto the support
at the same time, and the flatness may consequently be improved so
as to produce a film having a good surface condition, but also the
drying load may be reduced by virtue of use of dense cellulose
acetate solutions, and thereby the production speed of the film may
be improved.
In order to improve the mechanical characteristics, addition of a
plasticizer to a cellulose acetate film may be carried out.
Phosphate ester or carboxylate ester may be used as the
plasticizer.
Examples of the phosphate ester include triphenyl phosphate (TPP)
and tricresyl phosphate (TCP). Representatives of the carboxylate
ester include phthalate ester and citrate ester.
Examples of the phthalate ester include dimethyl phthalate (DMP),
diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate
(DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate
(DEHP).
Examples of the citrate ester include triethyl O-acetylcitrate
(OACTE) and tributyl O-acetylcitrate (OACTB).
Examples of other carboxylate esters include butyl oleate, methyl
acetyl ricinolate, dibutyl sebacate, and various trimeritate
esters.
The phthalate ester-base plasticizers (DMP, DEP, DBP, DOP, DPP,
DEHP) are preferably used. DEP and DPP are particularly
preferable.
Amount of addition of the plasticizer may preferably be 0.1 to 25%
by mass of cellulose ester, more preferably 1 to 20% by mass, and
most preferably 3 to 15% by mass.
The cellulose acetate film may preferably be subjected to surface
treatment.
Specific methods may be exemplified by corona discharge, treatment,
glow discharge treatment, flame treatment, acid treatment, alkali
treatment, and ultraviolet irradiation. Surface treatments which
can be employed in the invention are described in detail in
Hatsumei Kyokai Disclosure Bulletin 2001-1745, pp. 30-32, published
by Japan Institute of Invention and Innovation, Mar. 15, 2001.
An alkali-saponification treatment may be subjected to a cellulose
acetate film as follows. A cellulose acetate film is dipped in a
saponification solution, or a saponification solution is applied to
a surface of the film. Preferred is the latter. Examples of the
coating method include dip coating, curtain coating, extrusion
coating, bar coating and E-type coating. Alkali used for preparing
the saponification solution is preferably selected from hydroxides
of alkali metal (e.g., potassium and sodium). The concentration of
hydroxide ion in the solution is preferably from 0.1 to 3 N.
Wettability to the cellulose acetate film or stability of the
alkali-treatment liquid may be improved by employing a
wettability-rich solvent in preparing the liquid or adding any
surfactant or wetting agent (e.g., diols and glycerin) thereto.
Examples of the wettability-rich solvent to the film include
alcohols (e.g., isopropyl alcohol, n-butanol, methanol and
ethanol).
Additives to be added to the alkali treatment liquid are described
in JPA No. 2002-82226 and International Publication Pamphlet No.
WO02/46809.
In place of or addition to the surface treatment, an undercoating
layer may be formed on the polymer.
The undercoating layer may be formed according to a method
described in JPA No. hei 7-333433.
Multi-layered undercoating may be formed on the film. For example,
a multi-layered undercoating may be formed as follows. As a first
undercoating, a polymer layer having both of hydrophobic and
hydrophilic groups is formed on a surface of the film, and, as a
second undercoating, a polymer layer having a hydrophilic group,
which well-adheres an alignment layer, is formed on the first
undercoating. Such undercoatings may be produce according to a
method described in JPA No. hei 11-248940.
[Polarizing Plate]
According to the invention, the first or second optically
anisotropic layer may be stick to a surface of a linear polarizing
film (referred to as "polarizing film" hereinafter) to form a
polarizing plate, and then the polarizing plate may be used in
various applications.
The linear polarizing film may be selected from coating-type
polarizing films as typified by Optiva Inc., iodine-based
polarizing films and dichroic-dye based polarizing films. Iodine or
dichroic dye molecules are oriented in binder so as to have a
polarizing capability. Iodine or dichroic dye molecules may be
oriented along with binder molecules, or iodine molecules may
aggregate themselves in the same manner of liquid crystal and be
aligned in a direction.
Generally, commercially available polarizing films are produced by
soaking a stretched polymer film in a solution of iodine or
dichroic dye and impregnating the polymer film with molecules of
iodine or dichroic dye.
Generally, molecules of iodine or dichroic dye may enter into a
polymer film from the surface of the film and may be dispersed in
the area about 4 .mu.m in thickness from the surface of the film
(about 8 .mu.m in thickness from both of two surfaces of the film).
And in order to obtain sufficient polarizing ability, it is
required to use a polarizing film having a thickness not less than
10 .mu.m. The penetrance degree can be adjusted within a preferred
range by iodide or dichroic dye concentration of the solution,
temperature of the solution or soaking time.
The thickness of is not greater than those of commercially
available polarizing films (about 30 .mu.m), more desirably not
greater than 25 .mu.m and much more desirably not greater than 20
.mu.m. When a polarizing film having a thickness not greater than
20 .mu.m is used in a 17-inch liquid-crystal display, no light
leakage may be observed.
The polarizing film may comprise crosslinked binder.
Self-crosslinkable polymers may be used as binder. The polarizing
film may be produced by carrying out reaction between functional
groups of polymer with light, heat or variation of pH. Crosslinking
agents, which are compounds having high reaction-activities, may be
used.
Crosslinking reactions may be carried out by heating a coating
liquid comprising polymer or a mixture of polymer and a
crosslinking agent after being applied to a substrate. The heating
step may be carried out at any time by the end of the process for
producing the polarizing film as long as a final product having
good durability can be obtained.
Polymer to be used in the polarizing film as a binder may be either
of a polymer intrinsically crosslinkable itself, or a polymer
crosslinkable by a crosslinking agent.
Examples of the polymer include polymers such as polymethyl
methacrylate, polyacrylates, polymethacrylates, polystyrene,
polyvinyl alcohol and modified polyvinyl alcohol, poly(N-methylol
acrylamide), polyvinyltoluene, chlorosulfonated polyethylene,
nitrocellulose, chlorinated polyolefin, polyester, polyimide,
poly(vinyl acetate), polyethylene, carboxy methylcellulose,
polypropylene, and polycarbonate; and copolymers thereof (e.g.,
acrylate/methacrylate copolymer, styrene/maleimide copolymer,
styrene/vinyltoluene copolymer, and vinyl acetate/vinyl chloride
copolymer). Silane coupling agents are also employable.
Among these polymers, water-soluble polymers (e.g., poly(N-methylol
acrylamide), carboxymethyl cellulose, gelatin, polyvinyl alcohol
and modified polyvinyl alcohol) are preferred. Gelatin, polyvinyl
alcohol and modified polyvinyl alcohol are more preferred, and
polyvinyl alcohol and modified polyvinyl alcohol are even more
preferred.
The degree of saponification of the modified or non-modified
polyvinyl alcohol to be used in the invention is preferably 70 to
100%, more preferably from 80 to 100%, and even more preferably
from 95 to 100%. The degree of polymerization of the polyvinyl
alcohol to be used in the invention is preferably from 100 to
5000.
Examples of the modified polyvinyl alcohol include those modified
by copolymerization, chain transfer, or block polymerization.
Examples of modifier group involved in the modification by
copolymerization include --COONa, --Si(OX).sub.3 where X is a
hydrogen atom or alkyl), --N(CH.sub.3).sub.3.Cl, --C.sub.9H.sub.19,
--COO, --SO.sub.3Na and --C.sub.12H.sub.25. Examples of modifier
group involved in the modification by chain transfer include
--COONa, --SH and --SC.sub.12H.sub.25. The degree of polymerization
of the modified polyvinyl alcohol to be used in the invention is
preferably from 100 to 3000. Preferable examples of the modified
polyvinyl to be used in the invention include those described in
JPA Nos. hei 8-338913 and hei 9-152509. Among those, non-modified
or modified polyvinyl alcohols of which degree of saponification is
from 85 to 95% are especially preferred. Any combination of two ore
more types of non-modified or modified polyvinyl alcohols is
employable.
Examples of the crosslinking agent are described in U.S. reissued
Pat. No. 23,297. Boron compounds such as boric acid or pyroborate
can be used as a crosslinking agent. The amount of the crosslinking
agent is desirably from 0.1 to 20% by mass and more desirably from
0.5 to 15% by mass with respect to the mass of binder. When the
amount falls within the range, good alignment ability of molecules
of iodine and dichroic dye and good moisture-heat resistance can be
obtained. The polarizing film may contain some amount of unreacted
crosslinking agents after end of crosslinking reaction. The amount
of residual crosslinking agent in the polarizing film is desirably
not greater than 1.0% by mass and more desirably not greater than
0.5% by mass. When the amount falls within the range, the
polarization degree may not lower even if the polarizing film is
used for a long period or is left under a high-humidity and
high-temperature atmosphere for a long period.
Examples of dichroic dye include azo dyes, stilbene dyes,
pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine
dyes, thiazine dyes and anthraquinone dyes. The dichroic dye is
desirably selected from water-soluble dyes.
The dichroic dye desirably has a hydrophilic group such as sulfo,
amino or hydroxy.
More specific Examples of dichroic dye include C. I.
Direct.cndot.Yellow 12, C. I. Direct.cndot.Orange 39, C. I.
Direct.cndot.Orange 72, C. I. Direct.cndot.Red 39, C. I.
Direct.cndot.Red 79, C. I. Direct.cndot.Red 81, C. I.
Direct.cndot.Red 83, C. I. Direct.cndot.Red 89, C. I.
Direct.cndot.Violet 48, C. I. Direct.cndot.Blue 67, C. I.
Direct.cndot.Blue 90, C. I. Direct.cndot.Green 59 and C. I.
Acid-Red 37.
Dichroic dyes to be used in the invention are described in detail
in JPA Nos. hei 1-161202, hei 1-172906, hei 1-172907, hei 1-183602,
hei 1-248105, hei 1-265205 and hei 7-261024.
Dichroic dye may be used as a free acid or a salt (e.g., salts of
alkali metal, ammonium salts and amine salts). Various colored
polarizing films may be prepared by using two or more types of
dichroic dyes.
The polarizing film is prepared by stretching a polymer film in the
long direction, MD direction, or in other words according to a
stretching method, or by staining a polymer film with iodine or
dichroic dye, or in other words according to rubbing method.
According to the stretching method, the stretching ratio is
desirably from 2.5 to 3.0 and more desirably from 3.0 to 10.0. the
stretching process may be carried out under dried atmosphere, pr in
other words according to a dry stretching. Or the stretching
process may be carried out while being dipped in water, or in other
words according to a wet stretching. For the dry stretching, the
stretching ratio is desirably from 2.5 to 5.0, and for the wet
stretching, the stretching ratio is desirably from 3.0 to 10.0. The
stretching process may be divided into plural steps including an
obliquely stretching step. Dividing into plural steps, it is
possible to stretch uniformly even if the stretching ratio is high.
Before an obliquely stretching step, a stretching in a
width-direction or a stretching in a length-direction may be
carried out slightly (with a degree preventing shrinkage in a width
direction).
In terms of productivity, stretching may be carried out obliquely
in a direction 10 to 80 degree relative to the MD direction of a
polymer film. Such stretching may be carried out in a manner of a
tenter stretching employing biaxial-stretching steps at a left side
and a right side respectively.
The biaxial-stretching may be carried out according to a usual film
formation process.
For a biaxial stretching, a left side and a right side of a film is
stretched at a different ratio respectively, and, thus, the film
may be required to have different thicknesses at the left and right
sides respectively before being stretched. According to a
flow-casting method, it is possible to give a difference in a
flowing amount of a binder solution at a left side and a right side
by forming a taper on a die.
The stretching direction may be decided depending on its
application. Generally, the stretching direction is set at the
direction of 45.degree. relative to the MD direction.
Preferably, on both surfaces of a polarizing film, protective films
are disposed, and, as one of the protective films, an optical
compensation film, comprising the first and second optically
anisotropic layers, is disposed. Examples of such lamination
include a protective film/a polarizing film/the second optically
anisotropic layer/the first optically anisotropic layer, and a
protective film/a polarizing film/the second optically anisotropic
layer/alignment layer/the second optically anisotropic layer.
Preferably, a surface of the second optically anisotropic layer may
be stick to a surface of a polarizing film; alternatively, a
surface of the first optically anisotropic layer may be stick to a
surface of a polarizing film. The surfaces may be stick to each
other with adhesive. Examples of the adhesive include polyvinyl
alcohol based polymers (e.g., modified polyvinyl alcohols having
acetoacetyl group, sulfonic acid group, carboxyl group or
oxyalkylene group) and solutions of boron compounds. Among these,
polyvinyl alcohol based polymers are preferred.
The thickness of the dried adhesive layer is preferably from 0.01
to 10 .mu.m, and more preferably from 0.05 to 5 .mu.m.
To a surface of the polarizing plate, a light-diffusion film or an
anti-glare film may be stick.
<Light-Diffusion Film and Anti-Glare Film>
FIG. 1 is a frame format of a cross-section of a representative
embodiment of a light-diffusion film.
A light-diffusion film 101 shown in FIG. 1 comprises a transparent
base film 102 and a light-diffusion layer containing transparent
polymer 140 and first and second transparent fine particles
dispersed in the polymer 140.
It is to be noted that an embodiment employing two types of
transparent fine particles, having a refraction index different
from each other, of which particle-size distribution is different
from each other will be described in detail hereinafter, however, a
same type of transparent fine particles, having a same refraction
index, of which particle-size distribution is different from each
other, or one type of transparent fine particles may be also
employed. The first transparent fine particle 141 may be selected
from transparent polymer particles such as silica fine particles
(for example, fine particles having a mean particle size of 1.0
.mu.m and a refraction index of 1.51); and the second transparent
fine particle 142 may be selected from transparent polymer fine
particles such as polystyrene beads (for example, fine particles
having a mean particle size of 3.5 .mu.m and a refractive index of
1.61).
A light-diffusion property is ascribable to the difference between
refractive indices of transparent fine particles (141 and 142) and
transparent polymer (140). The difference of refractive index is
preferably from 0.02 to 0.15. The embodiment wherein the difference
of refractive index is equal to or more than 0.02 may achieve
light-diffusion more effectively; and the embodiment wherein the
difference of refractive index is equal to or less than 0.15 may
not achieve too light-diffusion and therefore reduce blushing as a
whole of the film itself. The difference of refractive index is
more preferably from 0.03 to 0.13, and even more preferably from
0.04 to 0.10.
The polarizing plate to be used in a liquid crystal display device
may have an anti-reflection layer on its viewed surface. The
anti-reflection layer may also function as a protective film.
In terms of reduction of colorant in the oblique direction, the
inner haze of the anti-reflection layer is preferably equal to or
more than 50%. The anti-reflection layer to be used in the
invention is described in detail in JPA Nos. 2001-33783,
2001-343646 and 2002-328228.
The retardation plate can be used as an elliptical polarizing plate
by combining with a polarizing film. The retardation plate can also
be used in combination with a polarizing film and applied to a
transmission, reflection or semi-transmission liquid crystal
display device to enhance the viewing angle. An elliptical
polarizing plate and a liquid crystal display device utilizing the
retardation plate will be described below.
[Elliptical Polarizing Plate]
An elliptical polarizing plate can be produced by laminating the
retardation plate and a polarizing film. An elliptical polarizing
plate capable of enhancing a viewing angle of a liquid crystal
display device can be provided by utilizing the retardation plate.
Examples of the polarizing film include an iodine polarizing film,
a dye polarizing film using a dichroic dye, and a polyene
polarizing film. The iodine polarizing film and the dye polarizing
film are generally produced by using a polyvinyl alcohol film. The
polarizing axis of the polarizing film corresponds to the direction
perpendicular to the stretching direction of the film.
The polarizing film is laminated on the side of the optically
anisotropic layer of the retardation plate. A protective film is
preferably provided on the surface of the retardation plate
opposite to the side where the polarizing film is laminated. The
protective film is preferably a transparent protective film having
a light transmittance of 80% or more. As the transparent protective
film, a cellulose ester film is generally used, and a triacetyl
cellulose film is preferably used. The cellulose ester film is
preferably produced by a solvent cast method. The protective film
preferably has a thickness of from 20 to 500 .mu.m, and more
preferably from 50 to 200 .mu.m.
[Liquid Crystal Display Device]
The retardation plate of the invention contributes to enhancement
of a viewing angle of a liquid crystal display device. The liquid
crystal display device generally comprises a liquid crystal cell, a
polarizing element and a retardation plate (optical compensation
sheet). The polarizing element generally contains a polarizing film
and a protective film, and the polarizing film and the protective
film may be those described for the elliptical polarizing plate. A
retardation plate (an optical compensation sheet) to be used for a
TN-mode liquid crystal cell is described in detail in JPA No. hei
6-214116, U.S. Pat. Nos. 5,583,679 and 5,646,703, and German Patent
Publication No. 3911620A1. A retardation plate to be used for an
IPS- or FDC-mode liquid crystal cell is described in detail in JPA
No. hei 10-54982. A retardation plate to be used for an OCB- or
HAN-mode liquid crystal cell is described in detail in U.S. Pat.
No. 5,805,253 and International Publication No. WO96/37804
Pamphlet. A retardation plate to be used for a STN-mode liquid
crystal cell is described in detail in JPA No. hei 9-26572. A
retardation plate to be used for a VA-mode liquid crystal cell is
described in detail in Japanese Patent Publication No. 2866372.
In the invention, liquid crystal cells employing various modes may
be produced referring to the descriptions in the above mentioned
publications. The retardation plate may be employed in various
liquid crystal display devices employing a TN (Twisted Nematic),
IPS (In-Plane Switching), FDC (Ferroelectric liquid Crystal), OCB
(Optically Compensatory Bend), STN (Super Twisted Nematic), VA
(Vertically Aligned) or HAN (Hybrid Aligned Nematic) mode. The
retardation plate may function more effectively for optical
compensation of a TN (Twisted Nematic) or OCB (Optically
Compensatory Bend) mode.
EXAMPLES
Paragraphs below will more specifically describe the present
invention referring to Examples. Any materials, reagents, amount
and ratio of use and operations shown in Examples may appropriately
be modified without departing from the spirit of the present
invention. It is therefore understood that the present invention is
by no means limited to specific Examples below.
Synthesis Example 1
Synthesis of Compound D3-12
The compound D3-12 was synthesized according to the following
scheme 1 by the same method as Example 11 disclosed in
WO2006/098489A1, pp. 72-73 and the compound D-227 disclosed in the
same publication, p. 77.
##STR00052##
The NMR spectrum of the resulting compound D3-12 was as
follows.
.sup.1H-NMR (solvent: CDCl.sub.3), standard substance:
tetramethylsilane) .delta. (ppm): 1.60 (6H, m), 1.80-1.90 (12H, m),
4.25 (6H, t), 4.45 (6H, t), 5.80 (3H, dd), 6.15 (3H, dd), 6.40 (3H,
dd), 7.65 (3H, t), 8.25 (3H, d), 8.45 (3H, d), 8.90 (3H, s), 9.30
(3H, s).
The resulting compound 3D-12 was measured for phase transition
temperatures by observing the textures thereof with a polarizing
microscope. As a result, when the temperature was increased, a
crystalline phase was changed to a discotic nematic liquid
crystalline phase at about 86.degree. C., and was changed to an
isotropic liquid phase when exceeding 142.degree. C. It was thus
found that the compound D3-12 exhibited a discotic nematic phase
within a range of from 86 to 142.degree. C.
Synthesis Example 2
Synthesis of Monomer A-6'
Monomer A-6'
##STR00053##
The monomer A-6' was synthesized according to the following scheme
2.
##STR00054##
300 g (2.41 mol) of ethylene glycol mono-2-chloroethyl ether
(available from Tokyo Kasei Kogyo Co., Ltd.) and 2 g of
nitrobenzene as a polymerization inhibitor were dissolved in 1,000
mL of ethyl acetate, to which 295 mL (3.65 mol) of acrylic chloride
was added dropwise over 3 hours under stirring and cooling with an
ice bath, followed by further stirring for 3 hours. After
completing the reaction, water was added to the reaction mixture,
which was then extracted with ethyl acetate, and the resulting
organic layer was washed with a saturated saline and dried over
sodium sulfate. The solvent was then removed from the organic layer
to obtain a product in an oily form (416 g, rough yield: 97%).
302 g (1.69 mol) of the resulting product was dissolved in 1,500 mL
of N,N-dimethylacetamide (DMAc), to which 360 g (2.60 mol) of
anhydrous potassium carbonate and 187.4 g (1.30 mol) of 2-naphthol
(available from Wako Pure Chemical Industries, Ltd.) were added and
dissolved therein, and the reaction mixture was heated to
90.degree. C. and stirred for 5 hours under a nitrogen atmosphere.
After completing the reaction, the reaction mixture was purified by
silica gel column chromatography and then recrystallized from a
mixed solvent of hexane/ethyl acetate (3/1) to obtain a monomer 1.
The monomer 1 will be referred to as the monomer A-6' hereinafter
(150 g, yield: 40%).
The NMR spectrum of the resulting monomer A-6' was as follows.
.sup.1H-NMR (solvent: CDCl.sub.3), standard substance:
tetramethylsilane) .delta. (ppm): 3.83 (2H, t), 3.92 (2H, t), 4.25
(2H, t), 4.37 (2H, t), 5.86 (1H, dd), 6.15 (1H, dd), 6.42 (1H, dd),
7.1-7.2 (2H, m), 7.32 (1H, t), 7.43 (1H, t), 7.75 (3H, m).
Synthesis Example 3
Synthesis of Monomer A-9'
Monomer A-9'
##STR00055##
The same procedures as in Synthesis Example 2 were carried out
except that 25 g of 6-cyano-2-naphthol (available from Sigma
Aldrich Japan, Inc.) was used instead of 2-naphthol (available from
Wako Pure Chemical Industries, Ltd.) used in Synthesis Example 2,
so as to obtain 30 g of 4-(2'-acryloyloxyethoxy)naphthalene
nitrile. The resulting compound will be referred to as the monomer
A-9' hereinafter (yield: 50%).
The NMR spectrum of the resulting monomer A-9' was as follows.
.sup.1H-NMR (solvent: CDCl.sub.3), standard substance:
tetramethylsilane) .delta. (ppm): 3.85 (2H, t), 3.95 (2H, t), 4.27
(2H, t), 4.37 (2H, t), 5.80 (1H, dd), 6.14 (1H, dd), 6.40 (1H, dd),
7.17 (1H, d), 7.29 (1H, dd), 7.55 (1H, dd), 7.7-7.8 (2H, m), 8.12
(1H, d).
Synthesis Example 4
Synthesis of Monomer A-7'
Monomer A-7'
##STR00056##
The same procedures as in Synthesis Example 2 were carried out
except that 2-(2-(2-chloroethoxy)ethoxy)ethanol (available from
Tokyo Kasei Kogyo Co., Ltd.) was used instead of ethylene glycol
mono-2-chloroethyl ether (available from Tokyo Kasei Kogyo Co.,
Ltd.) used in Synthesis Example 2, so as to obtain the monomer A-7'
(total yield: 75%).
The NMR spectrum of the resulting monomer A-7' was as follows.
.sup.1H-NMR (solvent: CDCl.sub.3), standard substance:
tetramethylsilane) .delta. (ppm): 3.60-3.80 (4H, m), 3.93 (2H, t),
4.25 (2H, t), 4.32 (2H, t), 5.82 (1H, dd), 6.14 (1H, dd), 6.40 (1H,
dd), 7.1-7.2 (2H, m), 7.30 (1H, t), 7.42 (1H, t), 7.72 (3H, m).
Synthesis Example 5
Synthesis of Monomer A-8
Monomer A-8'
##STR00057##
The same procedures as in Synthesis Example 2 were carried out
except that 21.6 g of 1-naphthol was used instead of 2-naphthol
(available from Wako Pure Chemical Industries, Ltd.) used in
Synthesis Example 2, so as to obtain 20 g of the monomer A-8'
(total yield: 50%).
The NMR spectrum of the resulting monomer A-8' was as follows.
.sup.1H-NMR (solvent: CDCl.sub.3), standard substance:
tetramethylsilane) .delta. (ppm): 3.88 (2H, t), 4.00 (2H, t), 4.32
(2H, t), 4.38 (2H, t), 5.80 (1H, dd), 6.14 (1H, dd), 6.42 (1H, dd),
6.82 (1H, d), 7.35 (1H, t), 7.40-7.50 (3H, m), 7.80 (1H, d), 8.28
(1H, d).
Synthesis Example 6
Synthesis of Polymer AD-1
The polymer AD-1 was synthesized according to the following
scheme.
##STR00058##
5 g of MEK was placed in a 100-mL three-neck flask and heated to
78.degree. C. under a nitrogen stream at a flow rate of 35 mL/min.
The monomers A-6' (9.6 g) and B-3' (6.4 g) and a solution of a
polymerization initiator (600 mg of V-601, produced by Wako Pure
Chemical Industries, Ltd.) in 8 g of MEK were added dropwise
thereto over 3 hours. After completing the dropwise addition, the
reaction was continued for 4 hours at the same temperature.
Thereafter, the reaction system was cooled to room temperature and
then added slowly to a methanol-water mixed solution (800 mL) under
stirring, and the polymer thus deposited was separated by
centrifugation and then dried. Thus, 10.5 g of the polymer (AD-1)
used in the invention was obtained. The polymer had Mn of 12,000
and Mw/Mn of 2.25 as measured with GPC (polystyrene standard). The
numerals attached to the constitutional units in the scheme each
represents the constitutional ratios thereof in terms of percent by
mass (which is hereinafter the same for the polymers synthesized in
Examples).
Polymers (AD-2) to (AD-5), having a polymerization ratio different
from that of Polymer (AD-1), were prepared in the same manner as
Synthesis Example 6.
Synthesis Example 7
Synthesis of Polymer AD-7
The polymer AD-7 was synthesized according to the following
scheme.
##STR00059##
5 g of MEK was placed in a 100-mL three-neck flask and heated to
78.degree. C. under a nitrogen stream at a flow rate of 35 ml/min.
The monomers A-6' (9.6 g), B-3' (3.2 g) and B-1' (3.2 g) and a
solution of a polymerization initiator (600 mg of V-601, produced
by Wako Pure Chemical Industries, Ltd.) in 8 g of MEK were added
dropwise thereto over 3 hours. After completing the dropwise
addition, the reaction was continued for 4 hours at the same
temperature. Thereafter, the reaction system was cooled to room
temperature and then added slowly to a methanol-water mixed
solution (800 mL) under stirring, and the polymer thus deposited
was separated by centrifugation and then dried. Thus, 13 g of the
polymer (AD-7) used in the invention was obtained. The polymer had
Mn of 10,900 and Mw/Mn of 2.04 as measured with GPC (polystyrene
standard).
Polymers (AD-6) to (AD-8), having a polymerization ratio different
from that of Polymer (AD-5), were prepared in the same manner as
Synthesis Example 7.
Polymers (AD-9) to (AD-11), having a molecular weight different
from that of Polymer (AD-5), were prepared in the same manner as
Synthesis Example 7, except that the amount of the
radical-polymerization initiator was increased or decreased.
Synthesis Example 8
Synthesis of Polymer AD-12
The polymer AD-12 was synthesized according to the following
scheme.
##STR00060##
4 g of MEK was placed in a 100-mL three-neck flask and heated to
78.degree. C. under a nitrogen stream at a flow rate of 35 mL/min.
The monomers A-6' (5.4 g), B-3' (5.2 g) and C-11' (5.4 g, Blemmer
AP-400, produced by NOF Corp.) and a solution of a polymerization
initiator (600 mg of V-601, produced by Wako Pure Chemical
Industries, Ltd.) in 8 g of MEK were added dropwise thereto over 3
hours. After completing the dropwise addition, the reaction was
continued for 4 hours at the same temperature. Thereafter, the
reaction system was cooled to room temperature and then added
slowly to 800 mL of a methanol-water mixed solution (10/90 by
volume) under stirring, and the polymer thus deposited was
separated by centrifugation and then dried. Thus, 13.8 g of the
polymer (AD-12) used in the invention was obtained. The polymer had
Mn of 11,000 and Mw/Mn of 2.14 as measured with GPC (polystyrene
standard).
Polymer (AD-13), having a polymerization ratio different from that
of Polymer (AD-12), was prepared in the same manner as Synthesis
Example 8.
Synthesis Example 9
Synthesis of Polymer AD-14
The polymer AD-14 was synthesized according to the following
scheme.
##STR00061##
4 g of MEK was placed in a 100-mL three-neck flask and heated to
78.degree. C. under a nitrogen stream at a flow rate of 35 mL/min.
The monomers A-6' (2.4 g), B-3' (4.8 g) and C-19' (7.2 g, NK Ester
AMP20G, produced by Shin-nakamura Chemical Corp.) and a solution of
a polymerization initiator (600 mg of V-601, produced by Wako Pure
Chemical Industries, Ltd.) in 8 g of MEK were added dropwise
thereto over 3 hours. After completing the dropwise addition, the
reaction was continued for 4 hours at the same temperature.
Thereafter, the reaction system was cooled to room temperature and
then added slowly to 800 mL of a methanol-water mixed solution
(10/90 by volume) under stirring, and the polymer thus deposited
was separated by centrifugation and then dried. Thus, 12.7 g of the
polymer (AD-14) used in the invention was obtained. The polymer had
Mn of 16,700 and Mw/Mn of 3.00 as measured with GPC (polystyrene
standard).
Synthesis Example 10
Synthesis of Polymer AD-15
The polymer AD-15 was synthesized according to the following
scheme.
##STR00062##
4 g of MEK was placed in a 100-mL three-neck flask and heated to
78.degree. C. under a nitrogen stream at a flow rate of 35 mL/min.
The monomers A-6' (9.12 g), A-9' (0.48 g) and B-3' (6.4 g) and a
solution of a polymerization initiator (600 mg of V-601, produced
by Wako Pure Chemical Industries, Ltd.) in 8 g of MEK were added
dropwise thereto over 3 hours. After completing the dropwise
addition, the reaction was continued for 4 hours at the same
temperature. Thereafter, the reaction system was cooled to room
temperature and then added slowly to 800 mL of a methanol-water
mixed solution (10/90 by volume) under stirring, and the polymer
thus deposited was separated by centrifugation and then dried.
Thus, 13.0 g of the polymer (AD-15) used in the invention was
obtained. The polymer had Mn of 14,700 and Mw/Mn of 2.98 as
measured with GPC (polystyrene standard).
Synthesis Example 11
Synthesis of Polymer AD-16
The polymer AD-16 was synthesized according to the following
scheme.
##STR00063##
4 g of MEK was placed in a 100-mL three-neck flask and heated to
78.degree. C. under a nitrogen stream at a flow rate of 35 mL/min.
The monomers A-6' (4.8 g), A-7' (4.8 g) and B-3' (6.4 g) and a
solution of a polymerization initiator (600 mg of V-601, produced
by Wako Pure Chemical Industries, Ltd.) in 8 g of MEK were added
dropwise thereto over 3 hours. After completing the dropwise
addition, the reaction was continued for 4 hours at the same
temperature. Thereafter, the reaction system was cooled to room
temperature and then added slowly to 800 mL of a methanol-water
mixed solution (10/90 by volume) under stirring, and the polymer
thus deposited was separated by centrifugation and then dried.
Thus, 13.7 g of the polymer (AD-16) used in the invention was
obtained. The polymer had Mn of 16,300 and Mw/Mn of 2.93 as
measured with GPC (polystyrene standard).
Synthesis Example 12
Synthesis of Polymer AD-17
The polymer AD-17 was synthesized according to the following
scheme.
##STR00064##
4 g of MEK was placed in a 100-mL three-neck flask and heated to
78.degree. C. under a nitrogen stream at a flow rate of 35 mL/min.
The monomers A-6' (4.8 g), A-8' (4.8 g) and B-3' (6.4 g) and a
solution of a polymerization initiator (600 mg of V-601, produced
by Wako Pure Chemical Industries, Ltd.) in 8 g of MEK were added
dropwise thereto over 3 hours. After completing the dropwise
addition, the reaction was continued for 4 hours at the same
temperature. Thereafter, the reaction system was cooled to room
temperature and then added slowly to 800 mL of a methanol-water
mixed solution (10/90 by volume) under stirring, and the polymer
thus deposited was separated by centrifugation and then dried.
Thus, 12.5 g of the polymer (AD-17) used in the invention was
obtained. The polymer had Mn of 13,000 and Mw/Mn of 2.30 as
measured with GPC (polystyrene standard).
Synthesis Example 13
Synthesis of Polymer AD-18
The polymer AD-18 was synthesized according to the following
scheme.
##STR00065##
4 g of MEK was placed in a 100-mL three-neck flask and heated to
78.degree. C. under a nitrogen stream at a flow rate of 35 mL/min.
The monomers A-6' (6.4 g), A-9' (3.2 g) and B-3' (6.4 g) and a
solution of a polymerization initiator (600 mg of V-601, produced
by Wako Pure Chemical Industries, Ltd.) in 8 g of MEK were added
dropwise thereto over 3 hours. After completing the dropwise
addition, the reaction was continued for 4 hours at the same
temperature. Thereafter, the reaction system was cooled to room
temperature and then added slowly to 800 mL of a methanol-water
mixed solution (10/90 by volume) under stirring, and the polymer
thus deposited was separated by centrifugation and then dried.
Thus, 13.7 g of the polymer (AD-18) used in the invention was
obtained. The polymer had Mn of 12,500 and Mw/Mn of 2.40 as
measured with GPC (polystyrene standard).
Example 1
Preparation of Composition (LM-1) of the Invention
The liquid crystal compound (1) (D3-12), the liquid crystal
compound (2) (T-8), the polymer used in the invention (AD-1),
Irgacure 907 (available from Ciba Specialty Chemicals Co., Ltd.) as
a photopolymerization initiator and diethylthioxanthone as a
photosensitizer were weighed according to the following formulation
and dissolved in methyl ethyl ketone to prepare a composition
(LM-1) of the invention.
TABLE-US-00003 Formulation of Composition (LM-1) Liquid crystal
composition (1) (D3-12) 91 parts by mass Liquid crystal composition
(2) (T-8) 9 parts by mass Polymer used in the invention (AD-1) 1.0
part by mass Irgacure 907 (available from Ciba 3.0 parts by mass
Specialty Chemicals Co., Ltd.) Diethylthioxanthone 1.0 part by mass
Methyl ethyl ketone 250 parts by mass
Example 2
Preparation of Compositions LM-2 to LM-17
The same procedures as in Example 1 were carried out except that
the polymer (AD-1) added to the liquid crystal compound (1) (D3-12)
and the liquid crystal compound (2) (T-8) was changed to the
polymers shown in Table 2 below, so as to prepare the compositions
(LM-2) to (LM-17) of the invention.
Example 3
Preparation of Composition (LM-18) of the Invention
The liquid crystal compound (1) (D3-12), the polymer used in the
invention (AD-18), Irgacure 907 (available from Ciba Specialty
Chemicals Co., Ltd.) as a photopolymerization initiator and
diethylthioxanthone as a photosensitizer were weighed according to
the following formulation and dissolved in methyl ethyl ketone to
prepare a composition (LM-18) of the invention.
TABLE-US-00004 Formulation of Composition (LM-18) Liquid crystal
composition (1) (D3-12) 100 parts by mass Polymer used in the
invention (AD-18) 1.0 part by mass Irgacure 907 (available from
Ciba 3.0 parts by mass Specialty Chemicals Co., Ltd.)
Diethylthioxanthone 1.0 part by mass Methyl ethyl ketone 250 parts
by mass
Comparative Example 1
Preparation of Comparative Compositions LH-1 to LH-4
The comparative composition LH-1 was prepared in the same manner as
in the preparation of the composition (LM-1) of the invention in
Example 1 except that the polymer (AD-1) was not added. The
comparative composition LH-2 was prepared in the same manner as in
the preparation of the composition (LM-18) of the invention in
Example 3 except that the polymer (AD-1) was not added. The
comparative compositions (LH-3) and (LH-4) were prepared in the
same manner as in the preparation of the composition (LM-1) of the
invention in Example 1 and the composition (LM-18) of the invention
in Example 3, respectively, except that the polymer ADH-1 shown
below (which was synthesized according to Example of JPA No.
2006-16599 mentioned above) was used instead of the polymer
(AD-1).
TABLE-US-00005 Liquid Liquid Crystal Crystal Compound Composition
Compound (1) (2) Polymer Example 1 LM-1 D3-12 T-8 AD-1 Example 2
LM-2 D3-12 T-8 AD-2 LM-3 D3-12 T-8 AD-3 LM-4 D3-12 T-8 AD-4 LM-5
D3-12 T-8 AD-5 LM-6 D3-12 T-8 AD-6 LM-7 D3-12 T-8 AD-7 LM-8 D3-12
T-8 AD-8 LM-9 D3-12 T-8 AD-9 LM-10 D3-12 T-8 AD-10 LM-11 D3-12 T-8
AD-11 LM-12 D3-12 T-8 AD-12 LM-13 D3-12 T-8 AD-13 LM-14 D3-12 T-8
AD-14 LM-15 D3-12 T-8 AD-15 LM-16 D3-12 T-8 AD-16 LM-17 D3-12 T-8
AD-17 Example 3 LM-18 D3-12 -- AD-18 Comparative LH-1 D3-12 T-8 --
Example 1 LH-2 D3-12 -- -- LH-3 D3-12 T-8 ADH-1 LH-4 D3-12 -- ADH-1
##STR00066## ADH-1 a/b = 26/74 (by mol), a/b = 34/66 (by mass) Mn =
16000, Mw/Mn = 2.51
Example 4
Production of Retardation Plate (RM-1) of the Invention
Production of Second Optically Anisotropic Layer (Transparent
Support)
The following components were placed in a mixing tank and dissolved
in each other by stirring under heating to prepare a cellulose
acetate solution.
TABLE-US-00006 Formulation of Cellulose Acetate Solution Cellulose
acetate (acetylation degree: 60.9%) 100 parts by mass Triphenyl
phosphate 7.8 parts by mass Biphenyldiphenyl phosphate 3.9 parts by
mass Methylene chloride 300 parts by mass Methanol 45 parts by
mass
Preparation of Retardation Increasing Agent Solution
4 parts by mass of cellulose acetate (linter) having an acetylation
degree of 60.9%, 25 parts by mass of the retardation increasing
agent (A) represented by the following formula, 0.5 part by mass of
silica fine particles (average particle diameter: 20 nm), 80 parts
by mass of methylene chloride and 20 parts by mass of methanol were
placed in another mixing tank and stirred under heating to prepare
a retardation increasing agent solution.
Retardation Increasing Agent
##STR00067##
18.5 parts by mass of the retardation increasing agent was mixed
with 470 parts by mass of the aforementioned cellulose acetate
solution, and the mixture was sufficiently stirred to prepare a
dope. The mass proportion of the retardation increasing agent with
respect to the cellulose acetate was 3.5% by mass.
Thereafter, a film having a remaining solvent amount of 35% by mass
was released from the band and then stretched transversally to a
stretching ratio of 38% at a temperature of 140.degree. C. with a
tenter. The film was released from the cramps and then dried at
130.degree. C. for 45 minutes to produce a cellulose acetate film
as the second optically anisotropic layer. The second optically
anisotropic layer thus produced had a remaining solvent amount of
0.2% by mass and a thickness of 88 .mu.m.
<Saponification Treatment of Second Optically Anisotropic
Layer>
A 1.5N isopropyl alcohol solution of potassium hydroxide was coated
on one surface of the second optically anisotropic layer thus
produced in an amount of 25 mL/m.sup.2, and after allowing to stand
at 25.degree. C. for 5 seconds, and the film was washed with
flowing water and the surface of the film was dried by blowing air
at 25.degree. C. Thus, only one surface of the second optically
anisotropic layer was saponified.
Formation of Alignment film
The alignment film coating composition having the following
formulation was coated on the saponified surface of the second
optically anisotropic layer with a #18 wire bar coater in an amount
of 31 mL/m.sup.2, and then dried with hot air at 100.degree. C. for
120 seconds.
The film thus formed was subjected to a rubbing treatment in a
direction at an angle of 45.degree. with respect to the stretching
direction of the second optically anisotropic layer (which was
substantially perpendicular to the retardation axis). The resulting
alignment film had a thickness of 0.5 .mu.m. The rubbing direction
of the alignment film was in parallel to the casting direction of
the transparent support.
TABLE-US-00007 [Formulation of Alignment film Coating Composition]
Modified polyvinyl alcohol (B) represented by the following 10
parts by mass formula Water 371 parts by mass Methanol 119 parts by
mass Glutaric acid aldehyde (crosslinking agent) 0.5 part by mass
##STR00068## ##STR00069## ##STR00070##
(Formation of Optically Anisotropic Layer)
The composition (LM-1) of the invention as a coating composition
was coated with a wire bar on the rubbing-treated surface of the
alignment film thus produced. The film having the optically
anisotropic layer coated was oriented in a constant-temperature
oven at 110.degree. C. and irradiated with an ultraviolet ray of
200 mJ/cm.sup.2 at that temperature to fix the orientation state of
the optically anisotropic layer, and then the film was cooled to
room temperature to provide a retardation plate (RM-1) of the
invention. The optically anisotropic layer thus formed had a
thickness of about 1.0 .mu.m.
Example 5
Production of Retardation Plates (RM-2) to (RM-17) of the
Invention
The retardation plates (RM-2) to (RM-17) were produced in the same
manner as in Example 4 except that the compositions (LM-2) to
(LM-17) were used instead of the composition (LM-1).
Example 6
Production of Retardation Plate (RM-18) of the Invention
The retardation plate (RM-18) was produced in the same manner as in
Example 4 except that the composition (LM-18) was used.
Comparative Example 2
Production of Comparative Retardation Plates (RH-1), (RH-2), (RH-3)
and (RH-4)
The retardation plates (RH-1) to (RH-4) were produced in the same
manner as in Example 4. except that the compositions (LH-1) to
(LH-4) were used instead of the composition (LM-1).
TABLE-US-00008 Retardation Plate Composition Example 4 RM-1 LM-1
Example 5 RM-2 LM-2 RM-3 LM-3 RM-4 LM-4 RM-5 LM-5 RM-6 LM-6 RM-7
LM-7 RM-8 LM-8 RM-9 LM-9 RM-10 LM-10 RM-11 LM-11 RM-12 LM-12 RM-13
LM-13 RM-14 LM-14 RM-15 LM-15 RM-16 LM-16 RM-17 LM-17 Example 6
RM-18 LM-18 Comparative RH-1 LH-1 Example 2 RH-2 LH-2 RH-3 LH-3
RH-4 LH-4
[Evaluation of Retardation Plates] (Measurement of Mean Tilt
Angle)
The Re value (589 nm) of the retardation plate produced was
measured by making light having a wavelength of 589 nm incident in
the normal line direction thereof in KOBRA 21ADH (produced by Oji
Scientific Instruments, Inc.). The retardation was then measured by
making light having a wavelength of 589 nm incident in a direction
tilted by +40.degree. with respect to the normal line direction of
the film with the in-plane retardation axis as the tilt axis, and
also measured by making light having a wavelength of 589 nm
incident in a direction tilted by -40.degree. with respect to the
normal line direction of the film. The tilt angle .theta.1 on one
surface of the optically anisotropic layer and the tilt angle
.theta.2 on the other surface thereof were calculated by fitting to
make the calculated retardation values of the optically anisotropic
layer depending on angle agree with the measured values with
.theta.1 and .theta.2 as parameters.
The mean tilt angle was obtained as an average value of .theta.1
and .theta.2 ((.theta.1+.theta.2)/2).
(Observation of Alignment State)
An ultrathin section of the cross section of the retardation plate
was produced with a microtome and was observed with a polarizing
microscope. It was thus confirmed that in the retardation plates
RM-1 to RM-11 of Examples and the retardation plates RH-1 and RH-2
of Comparative Examples, the liquid crystal molecules were in
hybrid orientation in the optically anisotropic layer. In the
retardation plates RH-3 and RH-4 of Comparative Examples, the
liquid crystal molecules were in horizontal orientation (mean tilt
angle: ca.) 0.degree. in the optically anisotropic layer.
(Temperature Dependency of Mean Tilt Angle)
The retardation plates were produced in the same manner as above
except that the optically anisotropic layer was heated to
80.degree. C. after orientation, and the orientation state was then
fixed with an ultraviolet ray. The retardation plates were measured
for the mean tilt angle in the same manner as above, and the
difference between the mean tilt angle where the orientation state
was fixed at 110.degree. C. and the mean tilt angle where the
orientation was fixed at 80.degree. C. was obtained as temperature
dependency of mean tilt angle.
The results obtained are shown in Table 4 below.
TABLE-US-00009 TABLE 4 Mean Mean Mean Tilt Retar- Tilt Tilt Angle
Alignment dation Angle Angle (Temp.- state Plate (110.degree. C.)
(80.degree. C.) Dependency) *1 Example 7 RM-1 35.degree. 34.degree.
1.degree. Hybrid Alignment RM-2 36.degree. 35.degree. 1.degree.
Hybrid Alignment RM-3 37.degree. 37.degree. 0.degree. Hybrid
Alignment RM-4 38.degree. 37.degree. 1.degree. Hybrid Alignment
RM-5 39.degree. 37.degree. 2.degree. Hybrid Alignment RM-6
26.degree. 25.degree. 1.degree. Hybrid Alignment RM-7 38.degree.
37.degree. 1.degree. Hybrid Alignment RM-8 39.degree. 39.degree.
0.degree. Hybrid Alignment RM-9 38.degree. 38.degree. 0.degree.
Hybrid Alignment RM-10 37.degree. 36.degree. 1.degree. Hybrid
Alignment RM-11 36.degree. 36.degree. 0.degree. Hybrid Alignment
RM-12 39.degree. 39.degree. 0.degree. Hybrid Alignment RM-13
30.degree. 33.degree. 3.degree. Hybrid Alignment RM-14 30.degree.
29.degree. 1.degree. Hybrid Alignment RM-15 29.degree. 30.degree.
1.degree. Hybrid Alignment RM-16 17.degree. 19.degree. 2.degree.
Hybrid Alignment RM-17 20.degree. 21.degree. 1.degree. Hybrid
Alignment RM-18 28.degree. 29.degree. 1.degree. Hybrid Alignment
Comparative RH-1 about about about 0.degree. Hybrid Example 3
44.degree. 44.degree. Alignment RH-2 about about about 1.degree.
Hybrid 44.degree. 43.degree. Alignment RH-3 about about about
0.degree. Homogenous 0.degree. 0.degree. Alignment RH-4 about about
about 0.degree. Homogenous 0.degree. 0.degree. Alignment *1:
Alignment State (Observation of the cross section of the
retardation plate)
It is understandable from the results shown in Table 4 that the
retardation plates (RM-1) to (RM-18) of the invention had mean tilt
angles controlled to a range of from 10 to 40.degree., as compared
to the retardation plates (RH-1) and (RH-2) of Comparative
Examples. It is also understandable that the mean tilt angles
thereof suffered less temperature dependency. It is further
understandable that the retardation plates (RH-3) and (RH-4) of
Comparative Example were in the homogenous alignment state, whereas
the retardation plates (RM-1) to (RM-18) of the invention were in
the hybrid alignment state.
It is understandable from the results that a hybrid alignment state
with a low tilt angle could be obtained by orienting molecules of a
discotic liquid crystal compound in the presence of the polymer
comprising the unit represented by formula (A) and the unit derived
from a monomer having a fluoroaliphatic group, and the tilt angle
suffered less fluctuation depending on temperature, whereby a
retardation plate having intended optical characteristics could be
stably obtained.
INDUSTRIAL APPLICABILITY
According to the invention, a composition, a polymer and a tilt
angle controlling agent can be provided that are useful for
producing stably an optically anisotropic layer contributing to
optical compensation of a liquid crystal display device. According
to the invention, in particular, an mean tilt angle of a discotic
liquid crystal compound in hybrid orientation can be controlled
precisely in a range of from 10 to 40.degree., and further in a
range of from 10 to 30.degree..
According to the invention, a retardation plate that is useful for
optical compensation of a liquid crystal display device, and a
process for producing the retardation plate are provided.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims benefit of priority under 35 USC 119 to
Japanese Patent Application No. 2007-064952 filed Mar. 13,
2007.
* * * * *